JP2018030267A - Image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation apparatus which can share the same cache memory for task processing in both of the real-time type and the best effort type while keeping the response accuracy of mechanism control at a high level.SOLUTION: A main control unit 60 of a MFP shares one cache memory 61M for execution of an image formation program 62R and another program 62B requiring the real-time property. A core 61C performs simulation execution of the image formation program 62R, and performs actual execution after completion of the simulation execution. The core 61C executes different commands according to printing conditions, shuts down control output to be transmitted to drive parts 10D-40D of mechanism units 10-40, creates response information from the drive parts 10D-40D thereto in a simulating manner in different modes according to the printing conditions, and locks down the information stored during the simulation execution in the cache memory 61M prior to the actual execution after completion of the simulation execution.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus, and more particularly, to use of a cache memory by a processor mounted thereon.

  Data processing required for the image forming apparatus is roughly divided into a real-time type and others. “Real-time type” refers to data processing that requires real-time performance. “Real-time” means both predictability of the maximum execution time of the task and certainty that the actual execution time does not exceed the maximum value. In an image forming apparatus, control of a mechanism unit used for image formation (hereinafter referred to as “mechanism control”) such as a sheet conveyance mechanism and a print engine is typical. Among data processing other than the real-time type, the best effort type is typical. In the image forming apparatus, image processing, user interface (UI), and network communication correspond to best-effort data processing. These processes do not necessarily require real-time performance, but versatility and extensibility (scalability) are strongly required.

  The required conditions differ between data processing of the real-time type and the other, particularly the best effort type. For the purpose of accurately responding to any of these conditions, in a conventional image forming apparatus, hardware (hereinafter referred to as a “mechanical controller section”) that performs mechanism control from its electronic control system (hereinafter referred to as “main control section”). , "Mechanical control part" for short). In particular, the main control unit and the mechanical control unit have their own microprocessor (CPU / MPU). By separating the two, for example, it is possible to devise such that the main control unit executes a general-purpose operating system (OS) and the mechanical control unit executes a real-time OS (RTOS) (see, for example, Patent Document 1). Since the main control unit can execute various application programs due to its high versatility, it can be easily multi-functionalized. Independently, the real-time performance is improved in the mechanical control unit, and the movement between the movable member such as the conveyance roller and the sheet can be controlled with a high response accuracy of about microseconds.

  In recent years, the performance of CPUs in embedded systems has increased significantly. In particular, application to a built-in system of a multi-core CPU and a hypervisor is progressing. In connection with this, development of the technique which reintegrates a mechanical control part to a main control part is tried (for example, refer to patent documents 2 and 3). By integrating the CPU, main memory, and other electronic circuit elements having the same function between the mechanical control unit and the main control unit, the number of parts of the electronic control system is reduced and the manufacturing cost of the image forming apparatus is reduced. The aim is to reduce. The “multi-core CPU” includes two or more “cores” that are circuit portions that actually perform operations. If the CPU is a multi-core, it is possible to cause a single CPU to execute an RTOS and a general-purpose OS in parallel by dividing the execution cores by OS (asymmetric multiprocessing: AMP). “Hypervisor” is software for operating one physical computer so that its hardware is shared by two or more virtual computers (virtual machines (VMs)). By causing the hypervisor to execute different OSs on different VMs, it is possible to physically execute RTOS and general-purpose OS in parallel on a single CPU.

JP 2004-265301 A JP, 2006-063407, A JP 2011-192130 A JP 2000-250518 A

  Since the CPU mounted on the main control unit uses a cache memory, in order to integrate the mechanical control unit into the main control unit, this cache memory must be made available for real-time task processing. Since the primary cache is independent for each core if the CPU is multi-core, the core dedicated to real-time task processing and the primary cache can be separated from those for other task processing. However, even in this case, since the secondary cache or the tertiary cache is generally shared by a plurality of cores, it is necessary to enable sharing between the real-time task process and other task processes.

  Using a cache memory for real-time task processing makes it difficult to predict task execution time because the CPU reads and writes instructions / data stochastically. Nevertheless, if the cache hit rate is sufficiently stable, the execution time can be predicted. However, when best-effort task processing is performed in parallel with real-time task processing, sharing of cache memory between the two processes significantly destabilizes the cache hit rate. This is because in the best effort type task processing, the usage amount of the cache memory greatly varies depending on the situation. As a result, it is difficult to predict the execution time of the real-time task, and it is difficult to guarantee a maximum execution time as short as when the mechanical control unit is separated from the main control unit. That is, when the mechanical control unit is integrated with the main control unit, it is difficult to maintain the response accuracy of the mechanism control at a high level of about microseconds.

  An object of the present invention is to solve the above-described problem, and in particular, an image that enables sharing of the same cache memory for both real-time and best-effort task processing while maintaining high response accuracy of mechanism control. It is to provide a forming apparatus.

  An image forming apparatus according to one aspect of the present invention is an image forming apparatus that shares one cache memory for execution of an image forming program that requires real-time processing and another program that does not necessarily require real-time processing. An execution means for performing a simulation execution of the image forming program and executing the image forming program after the simulation execution is completed; and a condition acquisition means for acquiring a printing condition to be followed during the execution prior to the simulation execution of the image forming program; During simulation execution, the execution unit reads out different commands and data from the image forming program according to the printing conditions acquired by the condition acquisition unit, and cuts off the control output to be transmitted from the execution unit to each part of the apparatus according to the command. Simulate the detection signal that should be sent according to the control output from the sensor provided in each part of the device Input / output simulation means created in different modes according to the printing conditions and passed to the execution means, and instructions and data stored in the cache memory prior to the actual execution after the simulation execution of the image forming program is completed. And a cache lockdown (CLD) means for locking down.

  The image forming apparatus includes a control unit including a main memory and a processor in addition to a cache memory, a mechanism unit that conveys a sheet and forms an image on the sheet being conveyed, and data from a user or an external electronic device. And an operation unit that accepts. The main memory may store an image forming program and other programs. The image forming program may include a program that causes the control unit to control the mechanism unit. The other program may include a program for causing the control unit to control the operation unit so that the operation unit functions as a condition acquisition unit. The processor may function as an execution unit, and may also function as an input / output simulation unit and a CLD unit by executing a simulation of an image forming program.

  The input / output simulation means may block the control output to be transmitted from the execution means to the mechanism section according to the access instruction by causing the execution means to skip the access instruction to the mechanism section among the instructions included in the image forming program. Good. The execution unit may simulate the image forming program during warming up or recovery of the mechanism unit. The execution unit may simulate the image forming program every time the condition acquisition unit updates the printing conditions.

  The input / output simulation means may change the mode of the detection signal to be created in accordance with at least one of the following items indicated by the printing conditions acquired by the condition acquisition means. (1) A sheet feeding place or a sheet discharging place. (2) Whether to indicate single-sided printing or double-sided printing. (3) Sheet size, paper type, or posture. (4) Which of the color mode and the monochrome mode is indicated? (5) Whether a post-processing device is externally attached.

  In the image forming apparatus according to the above aspect of the present invention, during simulation execution of the image forming program, the input / output simulation unit causes the execution unit to read different commands and data according to the printing conditions from the image forming program. The control output to be transmitted from the execution means is cut off according to the control output, and the detection signal that should be sent from the sensor in accordance with the control output is created in a different manner according to the printing conditions and passed to the execution means. After the simulation execution is completed, prior to the actual execution of the image forming program, the CLD means locks down the instructions and data stored in the cache memory during the simulation execution of the image forming program. As a result, in the actual execution of the image forming program, mechanism control is executed according to the instruction and data locked down in the cache memory. During this time, even if other data processing is executed in parallel for mechanism control, the instructions and data locked down in the cache memory are not overwritten with other instructions and data. Therefore, the cache hit rate in the mechanism control is stably maintained. Thus, the image forming apparatus can share the same cache memory for both real-time and best-effort task processing while maintaining high response accuracy of mechanism control.

FIG. 1A is a perspective view illustrating an appearance of an image forming apparatus according to an embodiment of the present invention. (B) is a schematic cross-sectional view of the image forming apparatus along a line bb shown in (a). FIG. 2 is a schematic diagram illustrating a sheet conveyance path formed by a conveyance mechanism of the image forming apparatus illustrated in FIG. 1. FIG. 2A is a perspective view of the image forming apparatus shown in FIG. 1 as viewed obliquely from the front, and FIG. 2B is a perspective view of the apparatus shown in FIG. FIG. 2 is a block diagram illustrating a configuration of an electronic control system of the image forming apparatus illustrated in FIG. 1. FIG. 5A is a block diagram illustrating a configuration of the cache memory illustrated in FIG. 4. (B) is a schematic diagram showing the data structure of the memory array shown in (a). (A) is a schematic diagram showing the operation of the cache memory when a cache miss occurs in a normal state. (B) is a schematic diagram showing the operation of the cache memory when a cache miss occurs in a state where a cache lockdown is instructed from the core. (A) is a schematic diagram showing the operation of the CPU immediately after the start of execution of the image forming program. (B) is a schematic diagram showing the operation of the CPU during the simulation execution of the image forming program. (A) is a schematic diagram showing the operation of the CPU during the main execution of the image forming program. (B) is a schematic diagram showing the operation of the CPU when the main execution of the image forming program is completed. (A) is a table | surface which shows the detection time of the sheet | seat by the paper passing sensor shown in FIG. 2 according to the combination of a sheet feeding place and a paper type. (B) is a table showing the time required for the sheet to pass through the sheet discharge sensor for each combination of sheet discharge location and paper type. (C) is a table showing the time required for the timing roller to pull out the trailing edge of the sheet from the detection range of the timing sensor for each combination of the sheet type, size, and orientation of the sheet. (D) is a table | surface which shows the time when the paper passing sensor detects a sheet | seat in each of single-sided printing and double-sided printing, and the operation time of the drive claw drive solenoid. (E) is a table showing motors to be driven in the print engine, regardless of whether the printer operation mode is the color mode or the monochrome mode. 5 is a flowchart of an image forming program execution process. It is a flowchart of control of a feeding roller group among the mechanism control by this execution in step S105 shown in FIG. 12 is a flowchart of a portion corresponding to the control of the feeding roller group shown in FIG. 11 in the mechanism control by the simulation execution in step S103 shown in FIG. FIG. 2A is a perspective view illustrating an external appearance of a relay unit and a post-processing device that are externally attached to the image forming apparatus illustrated in FIG. 1. FIG. 4B is a schematic diagram illustrating a sheet conveyance path built in the relay unit and the post-processing apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Appearance of image forming apparatus]
FIG. 1A is a perspective view showing an external appearance of an image forming apparatus 100 according to an embodiment of the present invention. This image forming apparatus is a multi-function peripheral (MFP) 100 and has functions of a scanner, a color copier, and a color laser printer. An automatic document feeder (ADF) 110 is mounted on the upper surface of the MFP 100 so as to be openable and closable. A scanner 120 is built in the upper part of the casing located directly under the ADF 110, and a printer 130 is built in the lower part of the casing. A paper feed cassette 133 is attached to the bottom of the printer 130 so that it can be pulled out.

  MFP 100 is an in-body discharge type. That is, a paper discharge tray 46 is installed in the gap DSP between the scanner 120 and the printer 130, and accommodates sheets discharged from the paper discharge port 42 at the back of the gap DSP. A reverse tray 47 is further installed on the paper discharge tray 46 in the gap DSP. At the time of duplex printing, the sheet on which the surface is printed is switched back on the reverse tray 47. That is, the sheet is once conveyed from the reversing port 44 opened above the paper discharge port 42 to a position where it protrudes onto the reversing tray 47, and then the conveyance direction is reversed and the sheet is again drawn into the reversing port 44.

[Mechanical part of image forming apparatus]
FIG. 1B is a schematic cross-sectional view of the MFP 100 along the line bb shown in FIG. As shown in this figure, the mechanism unit of the printer 130 is incorporated in the lower part of the casing of the MFP 100. The mechanism unit includes a feeding unit 10, an image forming unit 20, a fixing unit 30, and a paper discharge unit 40.

-Feeding section-
The feeding unit 10 uses the feeding roller groups 12P, 12R, 12F, 13, 14, and 15 to feed one sheet SH1 from the sheet bundle SHT stored in the sheet feeding cassettes 11a and 11b or the manual feed tray 16. The images are fed to the image forming unit 20 one by one. “Sheet” refers to a thin film or thin plate material, article, or printed material made of paper or resin. The types of sheets that can be accommodated in the paper feed cassettes 11a and 11b and the manual feed tray 16, that is, the paper type are, for example, plain paper, fine paper, color paper, or coated paper, and the sizes are, for example, A3, A4, A5. , B4, or B5. Furthermore, the posture of the sheet can be set to either vertical or horizontal.

-Image forming part (print engine)-
The image forming unit 20 forms a toner image on the sheet SH2 sent from the feeding unit 10. A print engine is used for this formation. The print engine includes, for example, four tandem image forming units 21Y, 21M, 21C, and 21K, an intermediate transfer belt 23, and a laser scanning exposure unit 26.

  First, the image forming units 21Y,... Uniformly charge the surfaces of the photosensitive drums 25Y, 25M, 25C, 25K, and the charged portions are irradiated with laser light to the exposure unit 26, and the axial directions of the photosensitive drums 25Y,. Scanning is performed in the direction normal to the paper surface in FIG. The amount of laser light is modulated by the tone value of one of the colors yellow (Y), magenta (M), cyan (C), and black (K) indicated by one line of the image data by the exposure unit 26. Yes. As a result, charge amount distributions corresponding to the gradation value distributions of different colors, that is, electrostatic latent images, are generated in the exposure areas on the different photosensitive drums. Next, each of the image forming units 21Y,... Charges the toner of any color among Y, M, C, and K and attaches it to the electrostatic latent image. Thus, different monochrome toner images appear on different photosensitive drums. The image forming unit 21Y,... Repeats such exposure and development while rotating the photosensitive drum 25Y,... By a predetermined angle for each different line of image data. Thus, the entire image represented by the image data is reproduced on each of the four photosensitive drums 25Y,... As a single color toner image of Y, M, C, K.

  The intermediate transfer belt 23 is stretched between the driving roller 23R and the driven roller 23L, and rotates with torque from the driving roller 23R. By this rotation, a certain surface area on the intermediate transfer belt 23 sequentially passes through the nip between the primary transfer rollers 22Y, 22M, 22C, 22K and the photosensitive drum 25Y,. In accordance with the passage timing of the surface area of the intermediate transfer belt 23, the monochrome toner image on the corresponding photosensitive drum 25Y,... Enters each nip and contacts the surface area. At this time, each toner image is transferred from the photosensitive drums 25Y,... To the surface area of the intermediate transfer belt 23 by the electric field between the primary transfer rollers 22Y,. In this way, four color toner images are superimposed on the surface area to form one color toner image. This color toner image passes through the nip between the driving roller 23R of the intermediate transfer belt 23 and the secondary transfer roller 24 simultaneously with the sheet SH2 sent from the feeding unit 10, and comes into contact with the sheet SH2. At this time, the color toner image is transferred from the intermediate transfer belt 23 to the sheet SH2 by the electric field between the rollers 23 and 24. Thereafter, the sheet SH2 is sent out to the fixing unit 30 by the drive roller 23R of the intermediate transfer belt 23.

  The exposure unit 26 includes four semiconductor laser elements as light sources, and emits light from each element by modulating the amount of current supplied to each element with the gradation values Y, M, C, and K indicated by the image data. Modulates the amount of laser light. Each laser beam is reflected by the polygon mirror 271 and transmitted through the fθ lens 273, and is reflected by the folding mirrors (28Y, 29Y), (28M, 29M), (28C, 29C), and 28K to be the target photosensitive drum 25Y, It is irradiated to ... At this time, the exposure unit 26 rotates the polygon mirror 271 with a motor 272 around its central axis (extending in the vertical direction in FIG. 1B) at a constant angular velocity. As a result, the incident angle of the laser light from the polygon mirror 271 to the fθ lens 273 changes at a constant speed. The fθ lens 273 is composed of, for example, two aspheric lenses, and forms an image of incident light from the polygon mirror 271 on the surface of each photosensitive drum 25Y,. Since the fθ lens 273 has a property that the image height is proportional to the incident angle, the image formation point moves along the axial direction on the surface of the photosensitive drum 25Y,. In b), it moves at a constant speed in the normal direction of the paper).

-Fixing part-
The fixing unit 30 heat-fixes the toner image on the sheet SH2 sent from the image forming unit 20. Specifically, the fixing unit 30 passes the sheet SH2 through the nip between both rollers while rotating the fixing roller 31 and the pressure roller 32. At this time, the fixing roller 31 applies heat of a built-in heater to the sheet SH2, and the pressure roller 32 applies pressure to the heated portion of the sheet SH2 and presses it against the fixing roller 31. Since the toner is welded to the sheet SH2 by the heat from the fixing roller 31 and the pressure from the pressure roller 32, the toner image is fixed to the sheet SH2. The fixing unit 30 further sends the sheet SH <b> 2 to the paper discharge unit 40 by the rotation of the fixing roller 31 and the pressure roller 32.

  The heater built in the fixing roller 31 is a halogen heater, for example, and is embedded in the core metal of the fixing roller 31. The fixing unit 30 monitors the outer peripheral surface temperature of the fixing roller 31 with a temperature sensor 35 installed in the vicinity of the fixing roller 31. For example, the temperature sensor 35 is a non-contact temperature sensor using a thermopile, and measures the outer peripheral surface temperature of the fixing roller 31 based on the amount of radiant heat from the outer peripheral surface of the fixing roller 31. The fixing unit 30 uses this measured value for controlling the amount of heat generated by the halogen heater.

-Output section-
The paper discharge unit 40 discharges the sheets SH <b> 3 and SH <b> 4 sent from the fixing unit 30 from the paper discharge port 42 to the paper discharge tray 46, or switches back by the reverse tray 47. Specifically, the paper discharge unit 40 first raises and lowers the switching claw 41 according to the sheet destination. The switching claw 41 is a claw-like or plate-like member whose base end is rotatably fixed between the paper discharge port 42 and the reversing port 44, and swings around the base end to move the tip up and down. Move to. When the leading edge of the switching claw 41 is raised, the sheet advances to the paper discharge port 42, and when it is lowered, the sheet advances to the reversing port 44. The paper discharge unit 40 then rotates the paper discharge roller 43 or the reverse roller 45. The paper discharge roller 43 is disposed inside the paper discharge port 42 and sends out the sheet SH3 that has passed through the switching claw 41 from the paper discharge port 42 to the paper discharge tray 46. The reversing roller 45 is disposed inside the reversing port 44 and can be rotated in both forward and reverse directions. The reversing roller 45 first rotates forward, and the sheet SH4 that has moved beyond the switching claw 41 is once sent from the reversing port 44 and placed on the reversing tray 47. The reversing roller 45 further reverses immediately before passing the rear end of the sheet SH4, pulls the sheet SH4 from the reversing tray 47 into the reversing port 44, that is, switches back and sends it to the circulation path 48. In the circulation path 48, the four pairs of transport rollers 49 </ b> A, 49 </ b> B, 49 </ b> C, and 49 </ b> D turn over the sheet SH <b> 5 sent by the reverse roller 45 and return it to the transport path in the feeding unit 10. Thereafter, the feeding unit 10 sends the sheet SH5 again to the image forming unit 20, and the image forming unit 20 forms a toner image on the back surface of the sheet SH5. The fixing unit 30 heat-treats the sheet SH5 again, and the paper discharge unit 40 sends the sheet SH5 to the paper discharge tray 46 this time.

-Sheet transport path-
In the MFP 100, in addition to the feeding unit 10 and the paper discharge unit 40, the image forming unit 20 and the fixing unit 30, such as the driving roller 23 </ b> R of the intermediate transfer belt 23, the secondary transfer roller 24, the fixing roller 31, and the pressure roller 32. A part of this also functions as a sheet transport mechanism.
FIG. 2 is a schematic diagram illustrating a sheet conveyance path formed by the conveyance mechanism. Three paper feed paths extending from the first stage 11a and the second stage 11b of the paper feed cassette and the manual feed tray 16 are combined into one path at the first junction MP1. This path passes through the image forming unit 20 and the fixing unit 30 and is divided into two at a branch point BP facing the switching claw 41. One is connected to the paper discharge tray 46 at the paper discharge port 42, and the other is connected to the reverse tray 47 and the circulation path 48 at the reverse port 44. The circulation path 48 is connected to the original path at a second junction MP2 located between the first junction MP1 and the image forming unit 20.

-Control of transport timing using paper feed sensor-
As shown in FIG. 2, in addition to the transport roller group 12P,..., Paper passing sensors 1FS, 2FS, CS, TS, ES, 1RS, and 2RS are installed on the transport path. Each of the sheet passing sensors 1FS,... Optically detects a sheet passing through the installation location and sends a signal indicating the sheet. Specifically, each paper passing sensor includes a light emitting unit and a light receiving unit. The light emitting unit emits light of a predetermined wavelength such as infrared rays, and the light receiving unit detects light of that wavelength and changes its output signal. While one sheet passes through the installation location of each sheet passing sensor, the sheet blocks the light emitted from the light emitting unit in front of the light receiving unit or reflects it toward the light receiving unit. Since the output signal of the light receiving unit changes according to the interception or reflection of the emitted light, the sheet passing through the installation location of each paper passing sensor is detected. The output signal, that is, the state of the detection signal of the sheet passing sensor 1FS,..., The feeding unit 10, the image forming unit 20, the fixing unit 30, and the sheet discharging unit 40 are described below with a main control unit 60 (see FIG. 4). To notify. In response to this notification, the main control unit 60 controls the timing of rotation and stop of the conveyance roller as described below, and determines whether or not an abnormality has occurred in the sheet conveyance timing due to a jam or the like. .

  In the vicinity of the sheet feeding cassettes 11a and 11b, a pickup roller 12P, a sheet feeding roller 12F, a separating roller 12R, and sheet feeding sensors 1FS and 2FS are installed. The feeding roller groups 12P, 12F, and 12R rotate intermittently when a plurality of sheets are continuously fed, and maintain the interval between consecutive sheets (paper interval) at a predetermined value. Depending on whether or not there is a delay in the sheet passing timing indicated by the outputs of the sheet feeding sensors 1FS and 2FS, the feeding roller groups 12P, 12F, and 12R send the sheets to the feeding path between normal sheets. It is determined whether or not.

A longitudinal conveyance roller 13 and a longitudinal conveyance sensor CS are installed in the feeding path from the second-stage sheet feeding cassette 11b. It is determined whether or not the vertical conveyance roller 13 is feeding the sheet to the first junction MP1 at a normal timing according to whether or not there is a delay in the sheet passing timing indicated by the output of the vertical conveyance sensor CS. .
Between the second junction MP2 and the secondary transfer roller 24, the timing roller 14 and the timing sensor TS are installed. The timing roller 14 is stopped when the sheet arrives from any of the paper feed cassettes 11a and 11b, the manual feed tray 16, and the circulation path 48, and temporarily stops the sheet. When the arrival of the sheet is detected from the output of the timing sensor TS, the timing roller 14 starts to rotate when a predetermined time elapses from the arrival time. As a result, the stopped sheet enters the nip between the driving roller 23R and the secondary transfer roller 24 of the intermediate transfer belt 23 simultaneously with the toner image on the intermediate transfer belt 23. It is determined from the output of the timing sensor TS whether or not there is a delay in the entry timing.

A paper discharge sensor ES is installed between the fixing unit 30 and the branch point BP. Depending on whether or not there is a delay in the sheet passing timing indicated by this output, whether or not the fixing roller 31 sends out the sheet at a normal timing and whether the sheet discharge roller 43 or the reverse roller 45 is normal. It is determined whether or not it is pulled in at a proper timing.
In the circulation path 48, paper passing sensors 1RS and 2RS are installed. Depending on whether or not there is a delay in the sheet passing timing indicated by these outputs, it is determined whether or not the transport roller group 49A-49D of the circulation path 48 is transporting the sheet at a normal timing.

-Actuator-
Actuators for driving movable members are installed around the transport path and the print engine. These actuators include transport motors M1-M6, TM, SM, FM, EM, RM, photosensitive drums 25Y,... Driving motors YM, MM, CM, KM, and a driving solenoid SL for the switching claw 41. Is included. Each drive motor M1,... Is, for example, a direct current brushless (BLDC) motor, and is generally rotatable in both forward and reverse directions. Each of the motors M1,... Gives a rotational force to the driving target roller through a transmission system such as a gear and a belt. The solenoid SL moves the movable iron core (plunger) back and forth in the axial direction by using an electromagnet and pushes and pulls the switching claw 41 to swing it up and down.

  In the vicinity of the paper feed cassettes 11a and 11b, the feed motors M1 and M2 rotate the feed roller groups 12P, 12F, and 12R. In the vicinity of the feeding path from the second-stage sheet cassette 11b, the longitudinal conveyance motor M3 rotates the longitudinal conveyance roller 13. In the vicinity of the feeding path from the manual feed tray 16, the feeding motor M <b> 4 rotates the feeding roller 15. The timing motor TM rotates the timing roller 14 near the second junction MP2. In the image forming unit 20, the main motor SM rotates the drive roller 23R of the intermediate transfer belt 23, and the four drive motors YM, MM, CM, and KM rotate the photosensitive drums 25Y,. In the fixing unit 30, the fixing motor FM rotates the fixing roller 31. In the paper discharge unit 40, the paper discharge motor EM rotates the paper discharge roller 43, and the reverse motor RM rotates the reverse roller 45 in both forward and reverse directions. The solenoid SL swings the switching claw 41 up and down. In the circulation path 48, one of the two drive motors, M5 rotates the two upstream conveying rollers 49A and 49B, and the other M6 rotates the two downstream conveying rollers 49C and 49D.

[Main control section]
3A is a perspective view of the MFP 100 from an oblique front, and FIG. 3B is a perspective view of the MFP 101 from the oblique rear. In any of the drawings, the main control unit 60 and the power supply unit 70 built in the MFP 100 are depicted as if they are seen through the casing and the chassis 101 of the MFP 100. The main control unit 60 and the power supply unit 70 are each mounted on a single printed circuit board, and these boards are placed in an electrical space ELS provided between the rear surface of the casing of the MFP 100 and the chassis 101. It is housed parallel to the back. Although not shown in FIG. 3, a connection portion (connector) for an external electronic device (option) is provided on the substrate of the main control portion 60. These options include portable storage devices PMD such as USB memory, hard disk drive (HDD), solid state drive (SSD), and function expansion boards EFB such as network (LAN) cards, semiconductor memory boards, graphic boards, etc. .

[Electronic control system of image forming apparatus]
FIG. 4 is a block diagram showing a configuration of the electronic control system of MFP 100. In this control system, in addition to the drive units 10D, 20D, 30D, and 40D in the mechanism units 10, 20, 30, and 40, the operation unit 50 and the main control unit 60 are connected through a bus 90 so as to communicate with each other. .
−Driver−
Although not shown in FIG. 4, the drive units 10D, 20D, 30D, and 40D of each mechanism unit 10,... Include a control circuit, a drive circuit, and a register. Using these, each drive unit 10D performs feedback control on actuators such as the drive motor group M1,..., Solenoid SL shown in FIG.

  The control circuit is an electronic circuit such as an MPU / CPU, an application specific integrated circuit (ASIC), or a programmable integrated circuit (FPGA). The control circuit determines the start and stop timing of the actuator and the target value of the control amount of the actuator, for example, the target rotational speed in the case of a drive motor. The control circuit further instructs the drive circuit of the target value of the voltage applied to the actuator based on the error between the determined control amount target value and the actual control amount fed back from the actuator.

The drive circuit is a switching converter, and a power transistor such as a field effect transistor (FET) or an insulated gate bipolar transistor (IGBT) is used as a switching element, and a voltage equal to the target value instructed by the control circuit is applied to the actuator. Apply. Thereby, the control amount of the actuator is adjusted to the target value.
The register is a memory element such as a latch circuit incorporated in the same substrate or the same chip as the control circuit. The register is monitored by both the control circuit and the main control unit 60, and is used as a temporary storage place for information to be exchanged between the two. The control circuit starts or stops the actuator in accordance with the command written in the register by the main control unit 60, and based on the information indicated by the command, such as the operation mode of the printer 130, the target value of the sheet conveyance speed, and the like, Determine the target value for the controlled variable. The control circuit also controls the information by writing information on the state of the actuator or the movable member to be driven or information on the state of the detection signal sent from the paper passing sensor 1FS to the register. Notification to the unit 60.

-Operation part-
The operation unit 50 is a total UI included in the MFP 100, and includes an operation panel 51, a memory interface (I / F) 52, and a network (LAN) I / F 53. Using these, the operation unit 50 receives various job processing requests from user operations or external electronic devices, and transmits the requests to the main control unit 60. In particular, when the job is printing, the operation unit 50 acquires the printing conditions together with the image data to be printed from the job processing request source. That is, the operation unit 50 functions as a condition acquisition unit. The print condition setting items include, for example, the size of the sheet to be printed, the paper type, the orientation (separately between portrait and landscape), the number of copies, color / monochrome, and image quality. The operation unit 50 incorporates values of parameters that define these conditions into the operation information, and provides them to the main control unit 60 together with image data to be printed.

  Operation panel 51 includes a push button, a touch panel, and a display. The operation panel 51 displays a graphics user interface (GUI) screen such as an operation screen and an input screen for various parameters on the display. The operation panel 51 also identifies what is pressed by the user from among the push buttons, or detects the position touched by the user from the touch panel, and transmits information related to the identification or detection to the main control unit 60 as operation information. . The memory I / F 52 includes a USB port or a memory card slot in the connector provided on the board of the main control unit 60 shown in FIG. 3, and directly from a portable storage device PMD such as a USB memory or HDD through them. Capture image data to be printed. The LAN I / F 53 communicates with an external network in a wired or wireless manner using a LAN card mounted on the board of the main control unit 60 shown in FIG. 3, and an electronic device such as a personal computer (PC) connected to the network. Receives the printing conditions and the image data to be printed.

−Main control unit−
The main control unit 60 is an integrated circuit mounted on one printed circuit board shown in FIG. 3 and includes a CPU 61 and a main memory 62. The CPU 61 is an execution unit for various programs. The main memory 62 includes a work area when the CPU 61 executes the program, together with a storage area for the programs.

  The CPU 61 is composed of one MPU, acquires various types of information such as operation information from the other elements 10, 20,... Through the bus 90 according to various programs, processes them, and generates a control output based on the processing results. It transmits to each element 10. “Control output” means a command to a transmission destination and data to be provided to the transmission destination. Thus, the CPU 61 functions as a control subject for these other elements 10. This function varies in various ways depending on the type of program to be executed. For example, the CPU 61 displays a GUI screen on the operation unit 50 and accepts a user operation on the screen. Based on the operation information notified from the operation unit 50 according to this operation, the CPU 61 determines the operation mode of the MFP 100 such as a print mode, a copy mode, a scan mode, a standby (low power) mode, a sleep mode, and the operation. The element 10 is instructed to shift to the mode. The CPU 61 further provides information necessary for switching the operation mode to the elements 10. For example, when instructing the shift to the print mode in response to a print job processing request, the CPU 61 instructs the feeding unit 10 to supply the paper type and number of sheets to be fed, the conveyance roller 12P according to the printing conditions in the job. ,..., The target value of the sheet conveyance speed is specified, the image forming unit 20 is provided with image data and image forming timing, the fixing unit 30 is supplied with the target temperature of the fixing roller 31, the heater 2 is designated, and the sheet delivery unit 40 is instructed to the sheet delivery destination from the branch point BP shown in FIG. 2 and the timing at which the sheet arrives at the branch point BP.

  The main memory 62 includes a RAM 621 and a ROM 622. The RAM 621 is a volatile semiconductor memory device such as a DRAM or SRAM, and provides a work area to the CPU 61 and stores image data to be printed received by the operation unit 50. The ROM 622 includes a combination of a non-writable nonvolatile storage device and a rewritable nonvolatile storage device. The former stores firmware. The firmware includes a boot program that the CPU 61 always executes first when the MFP 100 is powered on. The latter includes a semiconductor memory device such as an EEPROM, a flash memory, an SSD, or an HDD, stores various programs, and provides the CPU 61 with a storage area for data necessary for long-term storage such as environment variables. The programs stored in the ROM 622 include control programs for the ADF 110, the scanner 120, and the mechanism unit 10 of the printer 130, that is, a mechanical controller (also referred to as “mechanical controller” for short), an OS such as RTOS, and a hypervisor. Middleware and application programs using these as platforms are included.

  The entire storage area including the RAM 621 and the ROM 622 is mapped to one memory space. That is, a unique logical address is allocated to any storage area. Further, registers included in the drive units 10D of the mechanism units 10,... Are mapped in the memory space (memory mapped I / O). As a result, the CPU 61 can similarly execute the access to the registers of the mechanical units 10,... (Hereinafter referred to as “I / O access”) without distinguishing from the access to the main memory 62. That is, the CPU 61 can send an instruction to a mechanism unit having a register to which the address is assigned by writing a control output to a specific address in the memory space. The CPU 61 can also acquire information from the mechanism unit having the register to which the address is assigned, for example, the state of the detection signal sent from the sheet passing sensor 1FS,... By reading data from another address.

  Of the application programs stored in the main memory 62, the image forming program is executed in response to a print job processing request being notified from the operation unit 50 to the CPU 61. By this execution, the mechanical controller 62R is expanded in the RAM 621. The mechanical control 62R is a real-time type program that causes the CPU 61 to control the mechanical unit 10,... Of the printer 130, and its size is generally about several tens of KB.

  In addition, the application program includes a best effort type program 62B that causes the CPU 61 to control each of image processing, UI, and LAN communication. The size of each program 62B is generally several times that of the mechanical control 62R, that is, about several hundred KB to several MB. The image processing program causes the CPU 61 to execute, for example, color conversion from RGB to CYMK and halftone processing on the image data to be printed acquired by the operation unit 50. The UI program causes the CPU 61 to control the operation unit 50 so that, for example, the operation unit 50 functions as a condition acquisition unit.

[CPU architecture]
The CPU 61 includes a core 61C and a cache memory 61M. The core 61C is, for example, a RISC (reduced instruction set computer) processor, and particularly uses a load store architecture for program execution. That is, the core 61C performs processing such as computation only on the data read into the internal register. As a result, there are basically only two types of access to the main memory 62 and I / O access by the core 61C: reading data from the access destination (loading) and writing data to the access destination (store). Absent. The cache memory 61M includes a storage element, such as an SRAM, which has a small capacity as compared with the storage element included in the main memory 62, but which reads and writes at high speed. Specifically, the capacity of the RAM 621 is about several GB and the access time is about several hundreds of seconds, whereas the capacity of the cache memory 61M is about several tens of KB and the access time is about several tens of seconds. It is. The cache memory 61M is disposed in the middle of the data transmission path between the core 61C and the main memory 62, and stores the latest instruction and data read / written by the core 61C from / to the main memory 62. The cache memory 61M further provides the instruction / data to the core 61C on behalf of the main memory 62 when the instruction or data to be read / written from / to the main memory 62 is already stored by the core 61C, or Write to the main memory 62 instead of the core 61C. Since the cache memory 61M reads / writes faster than the main memory 62, the waiting time of the core 61C in reading / writing instructions / data can be shortened.

-Basic structure of cache memory-
FIG. 5A is a block diagram showing a configuration of the cache memory 61M. The cache memory 61M includes a cache controller 611 and a memory array 612. The cache controller 611 is hardware having a function of automatically reading and writing instructions and data (hereinafter collectively referred to as “words”) to and from the main memory 62 independently of the core 61C. Memory array 612 is a matrix of SRAM elements. When a load / store request is transmitted from the core 61C to the main memory 62, the cache controller 611 first intercepts the request before the request reaches the main memory 62. The cache controller 611 then checks whether the word stored at the destination address ADR of the request is already stored in the memory array 612. If the word is stored, the cache controller 611 sends the word CMD / DAT from the memory array 612 to the core 61C without passing the load / store request to the main memory 62, or the word in the memory array 612. Is rewritten to a word transmitted from the core 61C. If the word is not stored, the cache controller 611 passes the load / store request to the main memory 62. The word CMD / DAT is transferred from the main memory 62 to the core 61C in response to the load request, and the word is transferred from the core 61C to the main memory 62 in response to the store request. Is intercepted and copied to the memory array 612.

  FIG. 5B is a schematic diagram showing the data structure of the memory array 612. The memory array 612 includes, for example, 256 rows of memory element columns, that is, cache lines CLN0, CLN1,..., CLN255. Each cache line includes a directory store DRS, a status bit STT, and a data section DTS. A cache tag CTG is stored in the directory store DRS, and a plurality of words WRD0, WRD1,..., WRD3 are copied in the data section DTS. The cache tag CTG represents the upper bits of the address in the main memory 62 in which the original word WRD0,... Copied in the data section DTS is stored. The lower bits of the same address are expressed by a combination of the serial number of the cache line including the word (referred to as “set index”) and the order of the word in the data section DTS (referred to as “data index”). . If one word is represented by 32 bits and four words can be copied to one cache line, the entire memory array 612 can cache 4 KB words. The status bit STT includes a valid bit v and a dirty bit d. The valid bit v is a flag indicating whether or not the cache line including itself is valid, that is, whether or not the word WRD0,... In the data section DTS is the latest available one of the core 61C. . The dirty bit d is a flag indicating whether or not the word WRD0,... Copied in the data section DTS of the cache line including itself is different from the original in the main memory 62.

  FIG. 5B also shows a method for accessing the memory array 612 by the cache controller 611. When the cache controller 611 intercepts a load / store request, it first divides the destination address ADR into three: a tag field TGF, a set index field SID, and a data index field DID. When the destination address ADR is represented by a 32-bit data string ([31: 0]), the tag field TGF is composed of 20 bits ([31:12]) from the most significant bit of the address ADR to the 20th bit, The set index field SID is composed of 8 bits ([11: 4]) from the 21st bit to the 28th bit, and the data index field DID is composed of the remaining 4 bits ([3: 0]). Next, the cache controller 611 selects a cache line CLN2 having a set index equal to the value indicated by the set index field SID from the 256 cache lines CLN0,. The cache controller 611 compares the cache tag CTG stored in the directory store DRS with the tag field TGF of the destination address ADR. When the cache tag CTG matches the tag field TGF, the cache controller 611 further confirms the state of the valid bit v. When the valid bit v indicates that the cache line CLN2 is valid (this state is referred to as “cache hit”), the data section DTS of the cache line CLN2 includes the core 61C as a word stored in the destination address ADR. The latest available word has been copied. Therefore, the cache controller 611 does not pass the load / store request to the main memory 62, and transmits the word WRD1 whose data index is equal to the numerical value indicated by the data index field DID from the data section DTS to the core 61C, or the word WRD1. Rewrite the word CMD / DAT sent from the core 61C. When the cache tag CTG does not match the tag field TGF, or when the valid bit v indicates that the cache line CLN2 is invalid (this state is referred to as “cache miss”), the data section of the cache line CLN2 In the DTS, there is no word that can be used by the core 61C as the word stored in the destination address ADR. Accordingly, the cache controller 611 passes the load / store request to the main memory 62. The word CMD / DAT is transferred from the main memory 62 to the core 61C in response to the load request, and the word is transferred from the core 61C to the main memory 62 in response to the store request. Is copied to the data section DTS of the previous cache line CLN2 searched based on the destination address ADR.

-Cash lockdown-
FIG. 6A is a schematic diagram showing the operation of the cache memory 61M when a cache miss occurs in a normal state. When a cache miss occurs, the cache line CLNN searched by the cache controller 611 based on the destination address ADR generally stores a word of an address whose upper bits are different from the destination address ADR, although the lower bits match. The cache controller 611 confirms the state of the valid bit v of the cache line CLNN, and if the cache line is valid, for example, if v = 1, transitions to the invalid state v = 0, that is, the valid bit v is changed. Disable it. The cache controller 611 further confirms the state of the dirty bit d of the cache line CLNN. When the dirty bit d indicates that the word copied to the data section DTS is different from the original in the main memory 62, the cache controller 611 rewrites the original in the main memory 62 with the word CMD / DAT in the data section DTS. . Thus, the cache line CLNN is secured as an area for copying a new word transmitted from the main memory 62 or the core 61C.

  FIG. 6B is a schematic diagram showing the operation of the cache memory 61M when a cache miss occurs in a state where the cache lockdown is instructed from the core 61C. For the cache memory 61M, the core 61C functions as a cache lockdown means. “Cache lockdown (CLD)” means that the cache controller 611 is instructed to prohibit the invalidation of the valid bit v associated with a cache miss and the overwriting of a word in the data section DTS, or the cache after the prohibition. This refers to the state of the memory 61M. Therefore, a word that has already been copied to the memory array 612 at the time when the CLD is instructed from the core 61C is held in the memory array 612 without being overwritten by another word after that point even if a cache miss occurs. I.e. locked down. This state lasts until CLD release is instructed from the core 61C to the cache controller 611.

[Simulated execution and main execution of image forming program]
The CPU 61 executes an image forming program in response to a print job processing request. At this time, the CPU 61 first executes the image forming program by simulation, and executes the image forming program after completion of the simulation. “Full execution” refers to an execution mode for causing the printer 130 to perform normal printing processing. “Simulation execution” refers to an execution mode in which I / O access to the mechanism units 10,. During the simulation, the CPU 61 also functions as an input / output simulation unit. That is, the CPU 61 cuts off the control output to be transmitted to each of the mechanism units 10... And creates a simulation signal that should be transmitted from the sensor of the destination mechanism unit in accordance with the control output. As a result, during simulation execution, the CPU 61 does not actually have to wait for a response from any of the mechanism units, and therefore, the execution period of simulation execution, such as the processing time per sheet, is shortened compared to the main execution. After completion of the simulation execution, prior to the actual execution, the CPU 61 locks down the words of the mechanical control 62R stored during the simulation execution in the cache memory 61M. As a result, in this execution, the mechanical control is executed according to the word locked down in the cache memory 61M, and even if other programs are executed in parallel, those words are not overwritten with other words. Therefore, the cache hit rate in the mechanism control is stably maintained.

  FIG. 7A is a schematic diagram showing the operation of the CPU 61 immediately after the start of execution of the image forming program. First, the core 61C transmits a flush instruction CFL for the memory array 612 to the cache controller 611. In response to the instruction CFL, the cache controller 611 flushes the memory array 612. “Flush” refers to a process of invalidating the valid bit v (v = 1 → 0) in all the cache lines CLN0,. For the cache line CLNN where the dirty bit indicates that the word copied to the data section is different from the original in the main memory 62, the cache controller 611 uses the word CMD / DAT in the data section to store the word in the main memory 62. Rewrite the original. In this way, all the cache lines CLN0,... Are secured as new word copy areas.

  FIG. 7B is a schematic diagram showing the operation of the CPU 61 during the simulation execution of the image forming program. After the cache memory 61M has been flushed, the core 61C transmits a mechanical controller load request ADR to the main memory 62. The cache memory 61M intercepts the request ADR to determine a cache hit / miss, and when a miss occurs, the word CMD / DAT sent from the main memory 62 to the core 61C is copied to the memory array 612 in response to the request ADR. Thus, as the execution process proceeds, the memory array 612 caches the word CMD / DAT included in the mechanical controller.

  Of the words included in the mechanical control, the core 61C skips an I / O access command to the drive unit 10D of the printer 130. As a result, the core 61C does not read the words related to the I / O access from the main memory 62, so that the words cannot be cached in the memory array 612. However, the core 61C can block the command ACS to be written to the registers of the drive units 10D,. Further, the core 61C simulates the response information RSP, for example, information relating to the detection signal of the paper passing sensor 1FS,. These pieces of information are expected when the printing process proceeds normally, such as when the sheet passing sensor 1FS should detect the sheet when the sheet is normally conveyed without causing a problem such as a jam. Imitate response information. The core 61C uses these simulated response information RSP for mechanism control. Since the creation time of the simulated response information is shorter than the actual response time from the mechanism unit, the execution period of the simulated execution is shorter than the actual execution.

  FIG. 8A is a schematic diagram showing the operation of the CPU 61 during the main execution of the image forming program. After the printing process for a predetermined number of sheets such as one sheet is completed by the simulation execution, the core 61C first instructs the cache controller 611 to perform CLD. After receiving this instruction, the cache controller 611 does not invalidate the valid bit associated with a cache miss and overwrite the word in the data section. Therefore, Mechacon words copied to the memory array 612 during simulation execution are locked down to the memory array 612 without being overwritten by other words even if a cache miss occurs after that point. In this execution, among the instructions to be executed that meet the printing conditions included in the mechanical control, those other than the I / O access instruction for the drive unit 10D of the printer 130 are already cached in the memory array 612. Therefore, the cache hit rate in the mechanism control is maintained stably and substantially equal to 100%.

  FIG. 8B is a schematic diagram showing the operation of the CPU 61 when the main execution of the image forming program is completed. After the print processing of all sheets is completed by this execution, the core 61C first instructs the cache controller 611 to cancel CLD for CLD. After receiving this instruction, the cache controller 611 resumes the invalidation of the valid bit associated with the cache miss and the overwriting of the word in the data section. Therefore, the memory array 612 also caches programs other than mechanical controllers such as image processing, UI, and LAN communication.

[Changes in simulated response information depending on printing conditions]
During the simulation execution of the image forming program, the core 61C blocks the command ACS to be written to the register of the drive unit 10D,... Of the printer 130, and creates the response information RSP of the drive unit 10D,. . In the operation of the mechanism unit 10,... Of the printer 130 to be assumed at this time, details such as the timing actually differ depending on the printing conditions. For example, if the paper type of the sheet to be transported is different, the position of the sheet feed cassette and the target value of the sheet transport speed are different, so the sheet transport path and transport distance, and a sheet passing sensor that detects the sheet The position and the detection timing are different. Therefore, if the printing conditions are uniformly set to standard in the simulated execution, a cache miss due to the difference between the actual printing conditions and the standard one will delay the execution time and hit in this execution. There is a risk of hindering rate stabilization. In order to avoid this danger, the CPU 61 changes the response information RSP to be generated in a simulated manner according to the printing conditions during the simulation execution of the image forming program. Specifically, for example, the response information RSP is changed in accordance with at least one of the following items of the printing conditions. (1) A sheet feeding place or a sheet discharging place. (2) Whether to indicate single-sided printing or double-sided printing. (3) Sheet size, paper type, or posture. (4) Which of the color mode and the monochrome mode is indicated?

  FIG. 9A is a table showing sheet detection times by the sheet passing sensors 1FS, 2FS, CS, TS, and ES for each combination of sheet feeding location and sheet type. As apparent from FIG. 2, since the sheet conveyance path is different depending on whether the sheet feeding cassette is the first stage 11a or the second stage 11b, the sheet is fed by the sheet feeding sensors 1FS, 2FS and the longitudinal conveyance sensor. Whether or not to pass each CS is different. Next, since the lengths of the conveyance paths from the sheet feeding cassettes 11a and 11b to the timing roller 14 are different, after the sheet leaves the sheet feeding cassettes 11a and 11b, each of the timing sensor TS and the sheet discharge sensor ES is used. The time until detection is different. Furthermore, since the transport speed is different between plain paper and thick paper, the time detected by each sensor CS, TS, ES is different. Thus, the detection times by the sensors 1FS, 2FS, CS, TS, ES for each combination of the paper feed cassettes 11a, 11b and the paper type are TF1-TF2, TF3-TF4, TC3-TC4, TT1-TT4, TE1-. Different from TE4. These values represent the timing when the sheet is normally conveyed from the paper feed cassettes 11a and 11b to the paper discharge sensor ES. During simulation execution of the image forming program, the core 61C creates simulated response information RSP according to these values, and confirms that there is no delay in sheet conveyance from the paper feed cassettes 11a, 11b to the paper discharge sensor ES. This is used for adjustment between sheets by rotation / stop of the paper feed rollers 12P, 12F, and 12G, and control of the start timing of the timing roller 14.

  FIG. 9B is a table showing the time required for the sheet to pass through the sheet discharge sensor ES for each combination of the sheet discharge location and the sheet type. As is apparent from FIG. 2, depending on whether the paper discharge place is the paper discharge tray 46 or the reverse tray 47, first, the conveyance between the conveyance rollers 43 and 45 that apply a conveyance force to the sheet and the paper discharge sensor ES. Since the length of the path is different, the time from when the leading edge of the sheet is detected by the paper discharge sensor ES until reaching the transport rollers 43 and 45 is different, and then the trailing edge of the sheet passes through the paper discharge sensor ES. The time to do is different. Furthermore, since the transport speed differs between plain paper and thick paper, the time during which one sheet is detected by the paper discharge sensor ES differs. Thus, the passing time of the paper discharge sensor ES differs from PE1 to PE4 for each combination of the paper discharge locations 46 and 47 and the paper type. These values represent the timing when the sheet is normally conveyed from the fixing unit 30 to the paper discharge locations 46 and 47. During simulation execution of the image forming program, the core 61C creates simulated response information RSP in accordance with these values, confirms that there is no delay in sheet feeding from the fixing roller 31, the paper discharge roller 43 and the reverse roller. 45 is used to control the rotation / stop timing with the unit 45.

  FIG. 9C is a table showing the time required for the timing roller 14 to pull out the trailing edge of the sheet from the detection range of the timing sensor TS for each combination of sheet type, size, and orientation of the sheet. Since the length of the sheet along the conveying path differs depending on whether the posture is portrait or landscape, the sheet trailing edge is not detected by the timing sensor TS from the start of the rotation of the timing roller 14. The time until is different. Furthermore, since the conveyance speed differs between plain paper and thick paper, the time during which one sheet is detected by the timing sensor TS differs. Thus, the passing time of the timing sensor TS differs from PT1 to PT8 for each combination of sheet type, size, and orientation of the sheet. These values represent the timing when the timing roller 14 normally passes the sheet to the nip between the driving roller 23R of the intermediate transfer belt 23 and the secondary transfer roller 24. During simulation execution of the image forming program, the core 61C creates simulated response information RSP in accordance with these values, confirms that there is no delay in sheet feeding from the timing roller 14, and determines the timing for stopping the timing roller 14. Used for control.

  FIG. 9D is a table showing the time when the sheet passing sensors TS, ES, 1RS, and 2RS detect the sheet and the operation time of the drive solenoid SL of the switching claw 41 in each of single-sided printing and double-sided printing. . As shown in FIG. 2, unlike single-sided printing, in double-sided printing, the sheet is switched back at the reversing port 44, and then returns to the timing roller 14 through the circulation path 48. Therefore, first, whether or not a sheet passes through the paper passing sensors 1RS and 2RS is different between single-sided printing and double-sided printing. Next, the necessity of moving the tip of the switching claw 41 up and down is different. In this way, one sheet is detected only once by the timing sensor TS and the paper discharge sensor ES in single-sided printing, whereas twice in the timing sensor TS and paper discharge sensor ES in double-sided printing. Further, it is detected once for each of the paper passing sensors 1RS and 2RS in the circulation path 48. In addition, unlike single-sided printing, in double-sided printing, the drive solenoid SL operates twice for each sheet to move the tip of the switching claw 41 up and down. The values of the sheet detection times DT1, DT2, DE1, DE2, DR1, DR2, and the operation time of the drive solenoid SL in the duplex printing shown in the table of FIG. 9D are shown. TS1 and TS2 represent timings when the sheet is normally conveyed on the conveyance path during duplex printing, particularly the circulation path 48. During simulation execution of the image forming program, the core 61C creates simulated response information RSP according to these values, confirms that there is no delay in sheet conveyance in double-sided printing, and in sheet switchback at the reversing port 44 This is used to control the switching timing of the reverse rotation of the reversing roller 45.

  FIG. 9E is a table showing motors to be driven in the print engine, depending on whether the operation mode of the printer 130 is the color mode or the monochrome mode. As is apparent from FIG. 2, in the color mode, all of the four image forming units 21Y, 21M, 21C, and 21K create toner images, so that all the four photosensitive drums 25Y, 25M, 25C, and 25K rotate. On the other hand, in the monochrome mode, the color used is only one of Y, M, C, and K, for example, only K. Therefore, the photosensitive drum 25K rotates only in the corresponding image forming unit 21K. In the simulation execution of the image forming program, the core 61C simulates the rotational speed of the drive motors YM, MM, CM, KM of the photosensitive drums 25Y,... Shown in the table of FIG. It is incorporated in the RSP and used for controlling these drive motors YM.

A table as shown in FIG. 9 is incorporated in the image forming program together with the mechanical control. These tables are developed in the main memory 62 when the image forming program is simulated, as in the case of the mechanical control.
In general, the number of printing processes to be repeated during simulation execution is defined as a different value in accordance with printing conditions. For example, in single-sided printing, the entire mechanical control necessary for the printing process for one sheet is included, so the prescribed number of times may be set to “1”. On the other hand, in double-sided printing, if there are multiple sheets to be printed specified by the job, it is necessary until the control of the transport roller group becomes periodic throughout the transport path including the number of sheets and the circulation path 48. The specified number of times is set to the smaller of the number of printed sheets. This specified number of times is also incorporated in the image forming program, as in the table shown in FIG.

[Flow of image forming program execution processing]
FIG. 10 is a flowchart of an image forming program execution process. This process starts in response to the CPU 61 receiving a print job processing request from the operation unit 50.
In step S101, the core 61C transmits the flush instruction CFL for the memory array 612 to the cache controller 611. In response to the instruction CFL, the cache controller 611 flushes the memory array 612. As a result, the valid bit is invalidated in all the cache lines CLN0,. Thereafter, the process proceeds to step S102.

  In step S102, the CPU 61 develops the image forming program in the main memory 62, changes the parameter values necessary for creating response information in a simulated manner during the execution of the simulation, according to the printing conditions, and executes the main memory. Set to 62. Specifically, the core 61C decodes the print condition from the print job processing request from the operation unit 50, and the interval between the print condition item and the parameter value necessary for mechanism control as shown in the table of FIG. The parameter values are selected according to the printing conditions based on the corresponding relationship. Thereafter, the process proceeds to step S103.

  In step S103, the core 61C executes a simulation of the image forming program and performs a printing process for a predetermined number of sheets such as one sheet. In particular, the core 61C skips an I / O access command for the drive unit 10D of the printer 130 among words included in the mechanical control. Instead, the core 61C generates simulation information based on the parameter values prepared in step S102, from the drive units 10D,. As a result, the word included in the mechanical controller that the core 61C reads / writes from / to the main memory 62 is cached in the cache memory 61M, except for the I / O access command to the mechanism unit 10,. Thereafter, the process proceeds to step S104.

In step S104, after the simulation execution of the image forming program is completed, prior to the main execution, the CPU 61 causes the cache memory 61M to lock down the mechanical control word stored during the simulation execution. As a result, invalidation of the valid bit accompanying a cache miss and overwriting of a word in the data section are prohibited. Thereafter, the process proceeds to step S105.
In step S105, the core 61C executes the image forming program to print the number of sheets indicated by the print job. In this execution, among the instructions to be executed that meet the printing conditions included in the mechanical control, those other than the I / O access instruction to the mechanism unit 10 of the printer 130 have already been copied to the cache memory 61M. Since these instructions are locked down to the memory array 612 without being overwritten with other words even if a cache miss occurs, virtually all cache hits occur. Only the I / O access instruction is read from the main memory 62 in response to a cache miss at the first execution and cached in the cache memory 61M. Thereafter, the process proceeds to step S106.

  In step S106, the core 61C instructs the cache memory 61M to release the CLD after the print processing of all the sheets of the number specified by the print job is completed by the actual execution of the image forming program. As a result, the invalidation of the valid bit and the overwriting of the word to the data section due to the cache miss are resumed, so that the cache memory 61M is also opened to programs other than the mechanical control, such as image processing, UI, and LAN communication. . Thereafter, the process ends.

-Example of mechanical control processing in this execution-
FIG. 11 is a flowchart of control of the feeding roller groups 12P, 12F, and 12R in the mechanism control by the actual execution in step S105 shown in FIG. In this control, the feeding roller group 12P,... Is intermittently rotated to maintain the sheet interval at a predetermined value. Further, it is determined from the outputs of the paper feed sensors 1FS and 2FS, the vertical feed sensor CS, and the timing sensor TS whether or not there is a delay in the sheet passing timing and whether or not the sheet spacing is maintained at a normal value. The

  In step S201, the core 61C causes the feeding unit 10 of the printer 130 to start rotating the feeding roller group 12P of the paper feeding cassette 11a or 11b. Specifically, first, the core 61C writes a rotation command for the feeding roller group 12P,... In a register of the driving unit 10D of the feeding unit 10 according to the mechanical control. In the driving unit 10D, the control circuit monitors the register, and starts the feeding motor M1 or M2 in accordance with the rotation command written therein. Thereby, the feeding roller group 12P,... Starts rotating. Thereafter, the process proceeds to step S202.

  In step S202, the core 61C monitors the register of the driving unit 10D of the feeding unit 10 and confirms whether or not the output results of the paper passing sensors 1FS, 2FS, CS, and TS are written therein. If written, the core 61C further confirms whether or not the sheet has normally reached the timing roller 14 from the output results. If normal, the process proceeds to step S203, and if abnormal, the process proceeds to step S206.

  In step S203, the output results of the sheet passing sensors 1FS, 2FS, CS, and TS indicate that the sheet has reached the timing roller 14 normally. Accordingly, when a predetermined time has elapsed from the arrival time, the core 61C causes the feeding unit 10 to stop the rotation of the feeding roller group 12P,. Specifically, first, the core 61C writes a stop command for the feeding roller group 12P,... In the register of the driving unit 10D of the feeding unit 10 according to the mechanical control. The control circuit of the drive unit 10D stops the feed motor M1 or M2 in accordance with the stop command written in the register. Thereby, the feeding roller group 12P,... Stops rotating. Thereafter, the process proceeds to step S204.

  In step S204, the core 61C confirms whether or not there remains a sheet that has not been fed out from the sheet feeding cassette 11a or 11b by the feeding unit 10 among sheets to be printed. Specifically, first, the core 61C writes an output command for the number of sheets that the feeding roller group 12P,... Has finished feeding into the register of the driving unit 10D of the feeding unit 10. In response to this command, the core 61C acquires the number of sheets written by the control circuit of the drive unit 10D in the register, and checks whether the number is less than the number specified by the print job. If it remains, the process proceeds to step S205, and if not, the process ends.

  In step S205, there remains a sheet to be printed that has not yet been fed out from the paper feed cassette 11a or 11b. Therefore, the core 61C confirms whether or not the time necessary for opening the sheet interval has elapsed from the stop time of the feeding roller group 12P,. Specifically, first, the core 61C writes the output command of the elapsed time from the stop time to the register of the driving unit 10D of the feeding unit 10. In response to this command, the core 61C acquires the time value written by the control circuit of the driving unit 10D in the register, and compares the time value with a threshold value representing the time required to open the paper gap. If the time value is greater than or equal to the threshold, the process repeats from step S201, and if less than the threshold, the process repeats step S205.

  In step S206, the output result of any one of the sheet passing sensors 1FS, 2FS, CS, and TS does not indicate that the sheet has reached the timing roller 14 normally. Therefore, the core 61C confirms whether or not the time necessary for the sheet to normally reach the timing roller 14 has elapsed from the time when the sheet feeding roller group 12P,. If it has already elapsed, the process proceeds to step S207, and if it has not yet elapsed, the process is repeated from step S202.

  In step S207, the time necessary for the sheet to normally reach the timing roller 14 has already elapsed from the time when the sheet feeding roller group 12P has fed the sheet. Accordingly, the core 61C causes the operation unit 50 to display a notification indicating a jam on the operation panel, and instructs the mechanism unit 10 of the printer 130 to interrupt the printing operation. Thereafter, the process is stopped.

-Examples of mechanism control in simulated execution-
FIG. 12 is a flowchart of a portion corresponding to control of the feeding roller group 12P,... Shown in FIG. 11 in the mechanism control by the simulation execution in step S103 shown in FIG. In this control, the I / O access command for the driving unit 10D of the feeding unit 10 is skipped, and response information for the command is created in a simulated manner.

In step S <b> 211, the core 61 </ b> C skips the rotation command of the feeding roller group 12 </ b> P to the feeding unit 10 of the printer 130. Thereby, the rotation command to be written to the register of the driving unit 10D of the feeding unit 10 is blocked. Thereafter, the process proceeds to step S212.
In step S212, the core 61C simulates response information from the drive unit 10D of the feeding unit 10. This simulated response information is information to be read from the register in accordance with the writing of the rotation command to the register of the driving unit 10D in the present execution, specifically, each of the paper passing sensors 1FS, 2FS, CS, and TS. Mimics the output result. In particular, in this output result, for example, the core 61C calculated according to the detection time TF1,... By each sensor 1FS,... Shown in the table of FIG. The value which shows is described. Thereafter, the process proceeds to step S213.

  In step S213, the core 61C first skips monitoring the register of the driving unit 10D of the feeding unit 10. Next, the core 61C refers to the simulated response information created in step S212, instead of the response information that should be obtained by the monitoring, and the paper feed sensor 1FS or 2FS and timing sensor TS written therein are referred to. From the output result, it is confirmed whether or not the sheet has normally reached the timing roller 14. If normal, the process proceeds to step S214, and if abnormal, the process branches. However, since the simulated response information always indicates that the sheet has normally reached the timing roller 14, the process always proceeds to step S214.

  In step S214, the core 61C skips the stop command for the feeding roller group 12P,. In the case of this execution, this stop command should be sent when a predetermined time has elapsed from the time when the sheet reaches the timing roller 14. By this skip, the stop command to be written to the register of the driving unit 10D of the feeding unit 10 is blocked. Thereafter, the process proceeds to step S215.

  In step S215, the core 61C confirms the number of sheets that should have been fed out by the feeding unit 10 if this execution is performed. Specifically, first, the core 61C skips an output command for the number of sheets that the feeding roller group 12P,. Next, in response to this command, the core 61C generates simulated response information indicating the number of sheets that the control circuit would have written in the register of the driving unit 10D of the feeding unit 10, and the number of sheets is determined by the simulation execution. The core 61C confirms whether or not the printing process to be repeated is a prescribed number of times, for example, less than once. If it is less than the prescribed number of times, the process proceeds to step S216, and if above, the process ends.

  In step S216, since the number of printing processes repeated so far is still less than the prescribed number, the core 61C creates response information from the drive unit 10D of the feeding unit 10 in a simulated manner. This simulated response information indicates that the time required to open the sheet has elapsed from the stop time of the feeding roller group 12P in step S203. Thereafter, the process proceeds to step S217.

  In step S217, the core 61C confirms whether or not the time necessary for opening the paper interval has elapsed from the stop time of the feeding roller group 12P in step S203. Specifically, first, the core 61C skips the output command of the elapsed time from the stop time. Next, the core 61C refers to the simulated response information created in step S216 in place of the response information that should be acquired from the drive unit 10D according to the command, and compares the time value written therein with the threshold value. To do. If the time value is greater than or equal to the threshold, the process repeats from step S211, and if less than the threshold, the process repeats step S217. However, since the simulated response information always indicates a time value equal to or greater than the threshold value, the process is actually repeated from step S211.

[Advantages of the embodiment]
In MFP 100 according to the embodiment of the present invention, as described above, in response to a print job processing request, CPU 61 first executes a simulated program before the actual execution of the image forming program. In the simulation execution, the core 61C reads the words included in the mechanical controller from the main memory 62, and these words are cached in the cache memory 61M. However, since the I / O access command to the mechanism unit 10,... Of the printer 130 is skipped by the core 61C, if it is this execution, it should be transmitted from the core 61C to the drive unit 10D of the mechanism unit 10,. Control output is cut off. Instead, the core 61C simulates the response information that should be acquired from the drive units 10D,... According to the control output, and uses it for processing after I / O access. After the simulation execution is completed, the core 61C locks down the word stored during the simulation execution in the cache memory 61M prior to the actual execution. These words are used for mechanism control in this execution. These words are not overwritten by other words even if other programs are executed in parallel on the mechanical computer. Therefore, the cache hit rate in the mechanism control is stably maintained. Thus, the core 61C can share the same cache memory 61M for both real-time type and best effort type task processing while maintaining high response accuracy of mechanism control.

  In the simulation execution of the image forming program, the core 61C changes the mechanical control word read from the main memory 62 according to the printing conditions. The core 61C further changes the response information from the drive unit 10D, which is created in a simulated manner in accordance with the printing conditions, in accordance with the skip of the I / O access command to the mechanism units 10,. By using such printing conditions, among the words included in the mechanical controller, the words suitable for the printing conditions are locked down in the cache memory 61M, so the amount of data to be locked down in the cache memory 61M is optimized. . Furthermore, since the cache hit rate in this execution is stabilized at a high level, the maximum execution time of each task to be guaranteed in the mechanism control is shortened, and the response accuracy of the mechanism control is maintained at a high level of about microseconds. Is possible.

[Modification]
(A) The image forming apparatus 100 shown in FIG. 1 is an electrophotographic MFP. In addition, the image forming apparatus according to the embodiment of the present invention may be an inkjet multifunction device, or may be any single function device such as a laser printer, an inkjet printer, a facsimile machine, or a copier.

  (B) The structures shown in FIGS. 1B and 2 are merely examples, and other structures may be used. For example, the print engine may be a four-cycle method in which four image forming units are embedded in one rotating member instead of the tandem image forming units 21Y, 21M, 21C, and 21K. Further, the intermediate transfer belt 23 may be omitted, and the photosensitive drum may directly transfer the toner image to the sheet. The exposure unit may be an LD array type using a two-dimensional array of light emitting diodes (LDs) instead of the laser scanning type 26.

(C) The mechanical controller 62R shown in FIG. 4 is not limited to the mechanism unit 10 of the printer 130, and may be a mechanical controller including the ADF 110 and the scanner 120.
(D) The CPU 61 shown in FIG. 4 includes a single core 61C. Alternatively, the CPU 61 may be multi-core, and a specific core may be allocated exclusively for mechanism control by AMP. In this case, the primary cache may be independent for each core. The shared technology of the cache memory 61M in the task processing of both real-time type programs such as Mechacon and other (best effort) programs is a cache memory shared by a plurality of cores such as a secondary or tertiary cache. Applicable.

  (E) In the memory array 612 of the cache memory 61M shown in FIG. 5B, different set indexes 0 to 255 are allocated to all 256 cache lines CLN0,..., CLN255. In this case, only addresses having the same tag field TGF can be mapped to the memory array 612 at the same time among the address groups of the main memory 62 having the same set index field SID. That is, only words at those addresses can be cached simultaneously.

  In addition, the 256 cache lines included in the memory array 612 are divided into the same number, for example, 64 groups (referred to as “ways” or “segments”), and the same set index is allocated to the cache lines of different ways. May be. A group of cache lines having a common set index is called a “set”. A set index field, for example, an address group of the main memory 62 having a common middle 6 bits, can be mapped simultaneously to a maximum of the same number of ways as the number of ways.

  If memory array 612 contains only a single way as shown in FIG. 5B, cache lockdown will cause cache controller 611 to cache all cache lines as shown in FIG. This is realized by prohibiting both invalidation of the valid bit v due to a miss and overwriting of a word in the data section DTS. On the other hand, when the memory array 612 is divided into a plurality of ways, the cache controller 611 selects, for each set, a cache line (referred to as “victim”) whose valid bit should be invalidated at the next cache miss. Accordingly, the core 61C can realize cache lockdown in units of ways by designating the way to be excluded from the selection of victims to the cache controller 611. In the designated way, no cache line belonging to any set is selected as a victim, and therefore no word is overwritten on any cache line. Thus, the word is locked down in that way without overwriting the word into the data section.

  (F) A post-processing device may be externally attached to MFP 100. In this case, control of a mechanism unit included in the post-processing device is added to the print job processing. Therefore, in the simulated execution of the image forming program, the mechanical control of the post-processing apparatus may also be executed. In this case, since the items for specifying the necessity and type of post-processing are added to the printing conditions, response information from the post-processing device is created in a simulated manner in a different manner according to these items. May be.

  FIG. 13A is a perspective view showing the external appearances of the relay unit 140 and the post-processing device 150 that are externally attached to the MFP 100. The relay unit 140 is incorporated in the casing portion of the MFP 100 from which the relay tray 140 is removed instead of the paper discharge tray 46. The relay unit 140 receives a sheet from the paper discharge port 42 and relays it to the post-processing device 150. In response to an instruction from the MFP 100, the post-processing device 150 performs post-processing on a bundle of sheets received from the paper discharge outlet 42 through the relay unit 140. This post-processing includes, for example, processing for aligning a bundle of sheets and processing for binding the bundle with staples. Sheets are stacked on the upper discharge tray 151 of the post-processing apparatus 150 as they are delivered from the discharge outlet 42, and a bundle of sheets is aligned on the lower discharge tray 152 or closed with staples. Loaded.

  FIG. 13B is a schematic diagram illustrating a sheet conveyance path built in the relay unit 140 and the post-processing device 150. The paper discharge port 42 is connected to a route in the relay unit 140. Conveying roller groups 141, 142, and 143 are installed on this path, and the sheet sent from the paper discharge port 42 is relayed to the post-processing device 150. In the post-processing device 150, the paper feed roller 161 receives the sheet from the relay unit 140 and pulls it into the housing. The sorting claw 162 moves the tip up and down by swinging around its proximal end. As a result, the sorting claw 162 sorts the sheet pulled by the paper feed roller 161 to the upper paper discharge roller 163 or the vertical feed roller group 164. The upper paper discharge roller 163 discharges the sheet that has moved from the paper supply roller 161 along the sorting claw 162 to the upper paper discharge tray 151. The transport roller group 164 transports the sheet that has moved from the paper feed roller 161 along the sorting claw 162 toward the post-processing unit 166 to the reverse roller 165. The reversing roller 165 first rotates forward, and feeds the sheet sent by the transport roller group 164 to the post-processing unit 166. The reverse roller 165 then reverses and pulls out the post-processed sheet bundle from the post-processing unit 166. The post-processing unit 166 accumulates a predetermined number of sheets received from the reversing roller 165 to form a bundle, and performs post-processing such as alignment processing and staple binding processing on the bundle. The lower discharge roller 167 discharges the sheet bundle drawn from the post-processing unit 166 by the reverse roller 165 to the lower discharge tray 152.

  Although (b) in FIG. 13 is not shown, a plurality of paper passing sensors are also installed in the transport path between the relay unit 140 and the post-processing device 150. Using these sensors, the post-processing device 150 detects the position of the sheet being conveyed on the path and notifies the main controller 60 of the detected position. In response to this notification, the main controller 60 controls the driving motors or solenoids of the movable members 141-143 and 161-167 shown in FIG. For example, it is determined whether or not there is a delay in the sheet conveyance timing, and based on the determination, a conveyance failure such as a jam on the conveyance path between the relay unit 140 and the post-processing device 150 is detected.

In the simulation execution of the image forming program, a post-processing control program, particularly a control program for the movable members 141-143 and 161-167 shown in FIG. Words included in the post-processing control program are also cached in the cache memory 61M and locked down after the simulation execution.
In the simulation execution, the core 61C skips the I / O access command for the drive unit of the post-processing device 150 among the words included in the post-processing control program. On the other hand, in response to the command, the core 61C creates response information that the drive unit of the post-processing device 150 should write in its own register, for example, information related to the detection signal of the paper passing sensor, and uses it for control. This information is used for post-processing such as when the sheet passing sensor in the relay unit 140 and the post-processing device 150 should detect the sheet when the sheet is normally post-processed without causing a problem such as a jam. Mimic response information associated with normal progression of

  In particular, the core 61C changes the simulated response information according to the printing conditions. For example, since the sheet discharge destinations 151 and 152 differ depending on whether or not post-processing is necessary, the type of the transport roller to be driven and the direction of the tip of the sorting claw 162 are different. If the number of sheets per bundle is different, the target value of the conveyance speed of the bundle from the post-processing unit 166 is different, and therefore the rotation speeds of the drive motors for the reverse roller 165 and the lower discharge roller 167 are different. In accordance with these differences, the contents of the simulated response information such as the type of the sheet passing sensor that should detect the sheet and the timing of the detection are changed.

  In this way, when the simulation execution of the image forming program is completed, the words suitable for the printing conditions among the words included in the post-processing control program are locked down in the cache memory 61M. As a result, the amount of data to be locked down in the cache memory 61M is optimized. Furthermore, since the cache hit rate in this execution is stabilized at a high level, the maximum execution time of each task to be guaranteed in post-processing control is shortened, and the response accuracy of post-processing control is maintained at a high level of about microseconds. Is possible.

  The present invention relates to an image forming apparatus, and as described above, the main control unit 60 simulates and executes the program prior to the main execution of the image forming program, and locks down a portion of the program that meets the printing conditions in the cache memory 61M. To do. Thus, the present invention is clearly industrially applicable.

100 MFP
130 Printer 10 Feeding unit 11 Feed cassette 12P, 12F, 12R Feeding roller group 13 Vertical feeding roller 14 Timing roller 20 Image forming unit 21Y, 21M, 21C, 21K Photosensitive unit 22Y, 22M, 22C, 22K Primary transfer Roller 23 Intermediate transfer belt 23R Intermediate transfer belt drive roller 23L Intermediate transfer belt driven roller 25Y, 25M, 25C, 25K Photosensitive drum 24 Secondary transfer roller 26 Exposure unit 30 Fixing unit 31 Fixing roller 32 Pressure roller 40 Paper discharge Portion 41 Switching claw 42 Paper discharge port 43 Paper discharge roller 44 Reversing port 45 Reversing roller 46 Paper discharge tray 47 Reverse tray 50 Operation unit 51 Operation panel 60 Main control unit 61 CPU
61C Core 61M Cache memory 611 Cache controller 612 Memory array 62 Main memory 1FS, 2FS Paper feed sensor CS Vertical feed sensor TS Timing sensor ES Paper discharge sensor 1RS, 2RS Paper feed sensor

Claims (10)

An image forming apparatus sharing one cache memory for execution of an image forming program that requires real-time processing and another program that does not necessarily require real-time processing,
An execution means for executing the image forming program in a simulated manner and executing the image forming program after the simulation execution is completed;
Prior to the simulation execution of the image forming program, condition acquisition means for acquiring the printing conditions to be followed during the main execution;
During simulation execution of the image forming program, different instructions and data are read from the image forming program according to the printing conditions acquired by the condition acquisition unit, and the execution unit is transferred from the execution unit to each part of the apparatus according to the instructions. The control output to be transmitted is cut off, and a detection signal that should be sent according to the control output from a sensor provided in each part of the apparatus is created in a different manner according to the printing conditions and executed Input / output simulation means to be passed to the means;
A cache lockdown (CLD) means for locking down instructions and data stored in the cache memory prior to the actual execution after the simulation execution of the image forming program is completed;
An image forming apparatus. A control unit including a main memory and a processor in addition to the cache memory;
A mechanism that conveys the sheet and forms an image on the sheet being conveyed;
An operation unit for receiving data from a user or an external electronic device;
Further comprising
The main memory stores the image forming program and the other program,
The image forming program includes a program that causes the control unit to control the mechanism unit,
The other program includes a program that causes the control unit to control the operation unit so that the operation unit functions as the condition acquisition unit.
The image forming apparatus according to claim 1, wherein the processor functions as the execution unit and also functions as the input / output simulation unit and the CLD unit by simulating execution of the image forming program.   The input / output simulation unit causes the execution unit to skip an access command to the mechanism unit among commands included in the image forming program, so that the control to be transmitted from the execution unit to the mechanism unit according to the access command. The image forming apparatus according to claim 2, wherein the output is cut off.   The image forming apparatus according to claim 2, wherein the execution unit simulates and executes the image forming program during warm-up or recovery of the mechanism unit.   5. The image forming apparatus according to claim 2, wherein the execution unit simulates and executes the image forming program every time the condition acquisition unit updates a printing condition.   The input / output simulation unit changes a mode of a detection signal to be generated in a simulated manner in accordance with a sheet feeding place or a sheet discharge place indicated by a printing condition acquired by the condition acquisition unit. The image forming apparatus according to any one of claims 1 to 5.   The input / output simulation unit changes a mode of a detection signal to be simulated according to whether the printing condition acquired by the condition acquisition unit indicates single-sided printing or double-sided printing. The image forming apparatus according to claim 1.   The input / output simulation unit changes a mode of a detection signal to be generated in a simulated manner in accordance with a sheet size, a paper type, or a posture indicated by a printing condition acquired by the condition acquisition unit. The image forming apparatus according to claim 1.   The input / output simulation unit changes a mode of a detection signal to be simulated according to whether the printing condition acquired by the condition acquisition unit indicates a color mode or a monochrome mode. The image forming apparatus according to claim 1.   10. The input / output simulation unit changes a mode of a detection signal to be simulated in accordance with whether or not a post-processing device is externally attached. An image forming apparatus according to claim 1.

Images