JP6668966B2 - Image forming device - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to a technique for guaranteeing real-time performance when a cache memory is shared between real-time processing and best-effort processing.

2. Description of the Related Art Conventionally, image forming apparatuses are dedicated to executing best-effort processing such as image processing and graphical user interface (GUI) processing and real-time processing such as mechanical control during image formation. A CPU (Central Processing Unit) is mounted.
On the other hand, in recent years, the performance of a general-purpose CPU for an embedded system has been remarkably improved, and in combination with a demand for cost reduction, an image forming apparatus that performs both best-effort processing and real-time processing with a single CPU Has begun to be proposed.

Furthermore, in order to execute the best-effort processing and the real-time processing at high speed, it is effective to use a small-capacity, high-speed cache memory.
However, if the cache memory is shared between the real-time processing and the best-effort processing, the cache data of the real-time processing is cached out by the best-effort processing, and the real-time property of the mechanical control may be broken. For example, if the drive start of the transport roller downstream in the transport direction of the paper is delayed, the paper may be pressed against the stopped transport roller and a paper jam may occur.

  In order to solve such a problem, a configuration in which the use area of the cache memory is divided into a real-time process and a best-effort process may be considered. According to such a configuration, since the cache data of the real-time processing is not cached out by the best-effort processing, the real-time property of the mechanical control can be guaranteed.

JP-A-2000-250518

However, when the use area of one cache memory is divided between the real-time processing and the best-effort processing, the cache memory, which is originally small in capacity, is further divided, so that it is difficult to hit the cache and the effect of speeding up is reduced.
In order to prevent the real-time processing from being broken without partitioning the cache memory into a dedicated area, it is effective to lock down the real-time processing program. If cache lockdown is released after the real-time processing is completed, the cache memory can be used for the best effort processing, so that the speed can be increased.

  However, in order to cache-down the real-time processing program, it is necessary to execute the real-time processing program once and store it in the cache memory. In the execution of the real-time processing program, if a cache memory access conflict occurs with the best-effort processing, the real-time property of the mechanical control may be broken.

  SUMMARY An advantage of some aspects of the invention is to provide an image forming apparatus that reliably guarantees real-time mechanical control while performing cache lockdown of a real-time processing program. And

  In order to achieve the above object, an image forming apparatus according to the present invention provides an image forming apparatus that executes an image forming program that requires real-time processing and another program that does not necessarily require real-time processing by sharing one cache memory. An apparatus, wherein a stop unit for stopping the execution of the other program and a control output transmitted to each unit of the apparatus during execution of the image forming program are simulated to simulate a detection signal of a sensor provided in each unit of the apparatus. Input / output simulating means, a control cycle changing means for changing a control cycle of the image forming program relating to sheet conveyance, and an operation of the other program are stopped by the stopping means. The control output is cut off, the detection signal of the sensor is simulated, and the control cycle is changed by the control cycle changing means. Simulation execution means for simulating the image forming program in a state in which the image forming program is shorter than at the time of image formation, and at least the image forming section in the storage area of the cache memory prior to the main execution of the image forming program. Cache lock-down means for performing cache lock-down of an area storing a simulated execution location of a program; stop release means for releasing the operation stop of the other program after execution of the cache lock-down; And a cache lockdown release unit for releasing the cache lockdown after the execution.

According to this configuration, the image forming program is simulated while the operation of the other programs is stopped, so that the image forming program can be reliably stored in the cache memory. Thereafter, since the image forming program is actually executed in a state where the cache is locked down, the real-time property of the image forming process can be reliably guaranteed.
In this case, a transport sensor that detects the leading and trailing edges of the sheet transported during image formation is provided, and the input / output simulation unit simulates detection signals of the leading and trailing edges of the sheet by the transport sensor, The image forming program may be configured to calculate a sheet conveyance amount.

The image forming apparatus further includes an image forming unit for forming a toner image, and an image forming sensor that detects an image forming state of the image forming unit, and the input / output simulation unit simulates a detection signal of the image forming sensor. In this case, the image forming program may calculate the image forming position.
The image forming program may further include a mode information specifying unit that specifies mode information specified in the image forming job, and the simulation execution unit may simulate the image forming program according to the mode information.

In this case, the mode information may be information for specifying at least one of a paper feed port, a paper size, a color mode, a printing speed, and a printing surface. Furthermore, the simulation execution means may execute the image forming program after the mode information specifying means specifies the mode information.
Further, when the image forming program is subsequently executed after the actual execution of the image forming program, the simulation execution before the preceding actual execution after the preceding actual execution and the simulation execution before the subsequent actual execution are completed. Prohibition means for prohibiting release of cache lockdown may be provided.

In this case, if the mode information is different between the preceding main execution and the subsequent main execution of the image forming program, the prohibition unit must prohibit both the simulation execution and the release of the cache lockdown. It is even more suitable.
Other programs that do not require the real-time property include an image processing program and a user interface processing program that do not perform mechanical control.

FIG. 1 is a diagram illustrating a main configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing a main configuration of a control unit 100. 5 is a flowchart illustrating processing of a controller control core 201. It is a flowchart showing a mechanical control core interrupt process. 6 is a flowchart illustrating processing of a mechanical control core 202; It is a flowchart showing the process of the program for cache lockdown. 9 is a table illustrating a correspondence between mode information and simulation data. FIG. 2 is a diagram illustrating a main configuration of a transport system of the image forming apparatus 1. FIG. 2 is a diagram illustrating a configuration for driving a transport system of the image forming apparatus. It is a timing chart example at the time of simulation execution.

Hereinafter, embodiments of an image forming apparatus according to the present invention will be described with reference to the drawings.
[1] Configuration of Image Forming Apparatus First, the configuration of the image forming apparatus according to the present embodiment will be described.
As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment is a so-called tandem type color printer. The image forming apparatus 1 includes an image forming unit 110 and a paper feeding unit 120, and the image forming unit 110 includes an imaging unit 111. The imaging unit 111 receives toner of each color of yellow, magenta, cyan, and black from the toner bottle 112 to form a toner image, and performs primary transfer on the intermediate transfer belt 113 so that the toner images of each color overlap each other. A color toner image is formed.

  The intermediate transfer belt 113 conveys the color toner image to the secondary transfer roller pair 114. In parallel with this, the paper supply unit 120 supplies the paper stored in the paper supply cassette one by one. The color toner image is secondarily transferred onto the sheet from the intermediate transfer belt 113 at the secondary transfer nip of the pair of secondary transfer rollers 114, and is then thermally fixed in the fixing device 115 and discharged outside the apparatus. Note that the paper placed on the manual feed tray 121 may be used instead of the paper feed cassette.

The image forming unit 110 has a built-in control unit 100, and the control unit 100 controls each operation of the image forming apparatus 1.
[2] Configuration of Control Unit 100 Next, the configuration of the control unit 100 will be described.
As shown in FIG. 2, the control unit 100 includes a CPU 200, an HDD (Hard Disk Drive) 210, and the like. The CPU 200 is a so-called multi-core processor, and includes two cores 201 and 202 and a cache memory 203. In the present embodiment, the core 201 performs controller control, and the core 202 performs mechanical control.

  Here, the controller control refers to image processing and control of the entire image forming apparatus 1, and specifically includes image processing for acquiring image data and developing a bit map, and a network for communicating with a PC and other devices. It controls communication and an operation panel for receiving instructions from a user or the like. The controller control is a best-effort type process that performs a large amount of data processing by image processing and network communication, and a response from a user as fast as possible.

Further, the mechanical control controls mechanical control of the image forming apparatus 1 in order to execute an image forming process designated by the controller control. Specifically, the transport of a print medium and the control of a semiconductor laser are performed. Performs mechanical control such as control and temperature adjustment. Mechanical control is directly related to the quality of the printed image, and requires high real-time performance.
The cores 201 and 202 share a cache memory 203, a ROM (Read Only Memory) 220, a RAM (Random Access Memory) 221 and an HDD 210. The ROM 220 stores a boot program for activating the CPU 200 when the power of the image forming apparatus 1 is turned on. The RAM 221 is used as a work storage area of the CPU 200. The HDD 210 stores a controller control program 211 and a mechanical control program 212.

  The controller control core 201 reads the controller control program 211 from the HDD 210 and controls the controller control target unit 231 using the RAM 221 as a work storage area. The controller control target unit 231 is, for example, an image processing circuit, a network device, an operation panel, or the like. Further, the controller control core 201 instructs the mechanical control core 202 to execute an image forming process.

The mechanical control core 202 reads the mechanical control program 212 from the HDD 210 and controls the mechanical control target unit 232 via an I / O (Input / Output) control unit 233 using the RAM 221 as a work storage area. The mechanical control target part 232 is, for example, a motor, a clutch, a sensor, or the like.
I / O access from the mechanical control core 202 to the mechanical control control unit 232 is a so-called memory-mapped I / O. Therefore, a control output is performed by writing data to each address to which the register is mapped, and a sensor input can be obtained by reading data from the address.

  The I / O control unit 233 operates according to an instruction from the mechanical control core 202. During normal operation, the I / O control unit 233 causes the mechanical control core 202 to perform I / O access to the mechanical control target unit 232. Further, when the image forming process is simulated, the I / O control unit 233 does not allow the mechanical control core 202 to access the mechanical control target unit 232 and perform the I / O control regarding the image forming process. The internal memory of the control unit 233 is accessed.

The I / O control target unit 232 causes the mechanical control target unit 232 to perform I / O access to the mechanical control control unit 232 regarding processing other than the image forming process in both the actual execution and the simulation execution.
For this reason, when the mechanical control core 202 performs control output for the image forming process when the image forming process is simulated, the control content is written to the internal memory of the I / O control unit 233. When the mechanical control core 202 acquires a sensor input for the image forming process, the contents stored in the internal memory of the I / O control unit 233 are read. As a result, input / output required for the image forming process is simulated.

Hereinafter, among the operation modes of the I / O control unit 233, an operation mode in which the mechanical control core 202 accesses the mechanical control target unit 232 is referred to as a “normal mode”, and the mechanical control core 202 is defined as the I / O control unit 233. The operation mode for accessing the internal memory is referred to as a “simulation mode”.
The CPU 200 has a cache lockdown function. The cache lockdown function is a function that prohibits updating of an address registered in the cache memory 203 and continues caching access to an already registered address. The CPU 200, the HDD 210, the ROM 220, the RAM 221, the controller control target unit 231 and the mechanical control target unit 232 are connected to the internal bus 222 so that they can communicate with each other. The CPU 200 also arbitrates access to the internal bus 222.
[3] Cache Lockdown Processing Next, the cache lockdown processing according to the present embodiment will be described.

When performing cache lockdown, an image forming program that actually executes image forming processing is operated. However, if the image forming program is executed as usual, the motors and sensors operate, and the execution time is the same as during normal operation, and the productivity is reduced.
For this reason, a cache lockdown program that simulates sensor input during image formation is used. The cache lockdown program causes the mechanical control core 202 to execute the image forming program as usual, but does not perform control output related to motor and sensor control and image forming processes (charging, exposure, development, and transfer). Simulate the input.

  Also, the cache lockdown program shortens the control cycle of the image forming program and causes the simulation execution as described above. With this configuration, not only the real-time property of the image forming process can be reliably ensured, but also the cache lock-down of the image forming program can be performed in a short time. Therefore, the start of the image forming process can be more quickly started by suppressing the start delay of the image forming process than when the control cycle is not shortened.

In the image forming process, not all codes of the image forming program are necessarily executed, and codes to be executed may differ depending on the contents of the image forming job. That is, the code executed by the mechanical control core differs according to the specification of the paper size, color / monochrome, paper type, etc. specified in the image forming job. For this reason, when simulating the image forming program, the mode information provided for the actual execution is used as the simulating data.
(3-1) Basic Operation for Cache Memory 203 First, a basic operation when using the cache memory 203 will be described.

  When the cores 201 and 202 perform memory access to the ROM 220 and the RAM 221 when the cache memory 203 is enabled, the CPU 200 copies data read from the memory to the cache memory 203 in the case of reading, and When data is read from the same address, data (cache data) is read from the cache memory 203.

  In the case of writing, after data is once written to the cache memory 203, the data (cache data) is written to the original write destination address. In this way, the memory access to the cache memory 203 is performed at a higher speed than the memory access to the ROM 220 and the RAM 221, so that the cores 201 and 202 can operate at high speed. If the data to be accessed is stored in the cache memory 203, it is said that a cache hit has occurred.

  As a result of repeating the memory access, if there is no more free space for writing new data in the cache memory 203, new cache data is written to the area where the oldest cache data is stored. At this time, the old cache data is said to have been cached out. In order to access the cached data, it is necessary to access the ROM 220 and the RAM 221 again. Therefore, the memory access is not performed at high speed.

  Cache lockdown is a function that prevents cached data from being cached out. During cache lockdown, writing new data to the specified storage area of the cache memory 203 is prohibited, so the cache data stored in the specified area is not cached out, and access to the cache data is not performed. Always hit the cache.

  The cache memory 203 can also lock down the cache in only a part of the area. In this case, first, (a) cache lockdown is performed on an area other than the partial area, and (b) in this state, by accessing data to be cache locked down, cache lockdown is performed on the partial area. Write the data you want. When the writing is completed, (c) the cache lockdown of the partial area is performed, and then (d) the cache lockdown of the area other than the partial area is released.

By doing so, it is possible to write desired data to a partial area of the cache memory 203 and perform cache lockdown. Also, since the area other than the partial area is not cache locked down, it can be used when executing another program.
Therefore, if cache lockdown is performed while the mechanical control program 212 is stored in the cache memory 203, the mechanical control program 212 always hits the cache, so that real-time control of the mechanical control can be guaranteed.
(3-2) Operation of Controller Control Core 201 Next, an operation of the controller control core 201, particularly, an image forming process and a mechanical control core interrupt process will be described.
(3-2-1) Image Forming Process First, the image forming process will be described.

As shown in FIG. 3, when the controller control core 201 receives an image forming job from a user on the operation panel or receives an image forming job from another device such as a PC (Personal Computer) via a network. (S301: YES), the image data relating to the image forming job is acquired (S302).
In the image forming job, mode information is specified. The mode information includes, for example, a paper feed port of a paper, a paper size, a color mode, a printing surface, and the like. Next, the value of the work variable n representing the page number for image formation is set to 1 (S303), and the following loop processing is executed.

  First, image processing is performed on the image data of the n-th page (S304), and the image forming process of the n-th page is instructed to the mechanical control core 202 (S305). The instruction of the image forming process (hereinafter, referred to as “image forming instruction”) includes mode information specified in the image forming job. After that, the value of the variable n is increased by one, and the total number N of images formed for the image forming job is compared with the value of the variable n.

If the value of the variable n is equal to or less than N (S307: NO), the process proceeds to step S304 and the above processing is repeated. If the value of the variable n is larger than N (S307: YES), the process proceeds to step S301.
(3-2-2) Mechanical Control Control Core Interrupt Processing Next, mechanical control control core interrupt processing will be described.

The mechanical control core interrupt processing is started when the controller control core 201 receives an interrupt from the mechanical control core 202, and is executed by the controller control core 201.
As shown in FIG. 4, in the mechanical control core interrupt processing, the controller control core 201 refers to a predetermined address of the RAM 221 and checks whether or not the cache lockdown completion flag is set (S401). If the cache lockdown completion flag is not set (S402: NO), it is determined that the cache lockdown processing by the mechanical control core 202 has not been completed yet, so the process proceeds to step S401, and the cache lockdown completion flag is further increased. To monitor.

If the cache lockdown completion flag has been set (S402: YES), it is determined that the cache lockdown processing by the mechanical control core 202 has been completed, the cache lockdown completion flag is reset (S403), and the interrupt processing ends. Then, the process returns to the normal process.
With this configuration, while the mechanical control core 202 is performing the cache lockdown process, the controller control core 202 only repeats the process of referring to the cache lockdown completion flag. Will not be cashed out.
(3-3) Image Forming Process by Mechanical Control Core 202 Next, an image forming process by the mechanical control core 202 will be described.

  As shown in FIG. 5, upon receiving an image forming instruction from the controller control core 201 (S501: YES), the mechanical control core 202 starts a print preparation operation (S502). Next, a mechanical control core interrupt is input to the controller control core 201 (S503), and the controller control core 201 is shifted to a standby state by interrupt processing.

  As a result, rewriting of the cache memory 203 by the controller control core 201 is suppressed, so that the cache lockdown program is executed (S504). Note that, after completion of the process of step S503 and before the start of the process of step S504, the storage area of the cache memory 203 that is to be locked down may be cleared.

When the execution of the cache lockdown program is completed, cache lockdown is performed (S505), and a cache lockdown completion flag is set (S506). As a result, the controller control core 201 exits the standby state due to the interrupt processing and returns to the normal operation state.
Next, the mechanical control core 202 executes the image forming process (S507), and when the image forming process is completed, checks whether or not an image forming instruction for the next page has been received from the controller controlling core 201. If the image forming instruction for the next page has been received (S508: YES), it is checked whether the mode information of the current page and the next page match the image forming instruction.

When the mode information is changed (S509: YES), the cache lockdown is temporarily released (S510), and the process proceeds to step S503. By doing so, the image forming program can be stored in the cache memory 203 in accordance with the mode information of the next page, so that real-time processing of the image forming process of the next page can be guaranteed.
If the mode information has not been changed (S509: NO), the flow advances to step S507 to execute the image forming processing for the next page. In this case, by using the image forming program stored in the cache memory 203, it is possible to guarantee real-time processing for the image forming processing of the next page.

If the image formation instruction for the next page has not been received (S508: NO), the cache lockdown is released (S511), and the process proceeds to step S501 to wait for the next image formation instruction.
(3-4) Cache Lockdown Program Next, a cache lockdown program will be described.

  The mechanical control program 212 executed by the mechanical control core 202 includes an image forming program and a preparation processing program. The image forming program executes mechanical control necessary for the image forming process. Specifically, it is determined at regular intervals whether or not a control output is required by referring to the sensor input, and the control output is performed if necessary. This cycle is called “control cycle”. The preparation processing program executes, for example, a warm-up process of the fixing device 115 before executing the image forming process.

  The cache lockdown program uses the I / O control unit 233 to stop the control output by the mechanical control core 202 or simulate a sensor input to the mechanical control core 202. Thus, the image forming program can be simulated and the image forming program can be stored in the cache memory 203 without actually operating the mechanical control target unit 232.

The cache lockdown program shortens the control cycle of the image forming program, thereby reducing the time required for simulating the printing process. Therefore, it is possible to suppress an increase in FCOT (First Copy Out Time) due to cache lockdown processing.
That is, as shown in FIG. 6, first, simulation data used for simulating execution of an image forming program is generated based on mode information included in an image forming instruction from the controller control core 201 (S601). FIG. 7 is a table illustrating the correspondence between the mode information and the simulation data. As shown in FIG. 7, the simulation data of the paper feed port is generated from the specification of the paper feed port in the mode information.

Also, from the specification of the paper size in the mode information, the paper length is generated as simulation data in units of 1/100 mm. A paper leading edge position is generated from the color mode. Further, from the paper feed port and the paper length generated from the mode information, the initial values of the paper leading end position and the paper trailing end position are determined in 1/100 mm units as the paper feed timing.
Further, depending on the color mode, for example, of the imaging units 111 for forming four color toner images of yellow (Y), magenta (M), cyan (C) and black (K), only the K color imaging unit 111 is operated. It is determined whether to operate only the imaging unit 111 for all colors of YMCK. The paper transport amount per control cycle is determined from the print speed. From the printing surface, it is determined whether to pass one side or both sides.

Next, the cache lockdown program shortens the control cycle of the image forming program (S602). For example, if the control cycle during normal image formation is 5 milliseconds, the control cycle during simulation execution may be set to 2.5 milliseconds.
The cache lockdown program further sets the I / O control unit 233 to the simulation mode (S603). In this case, the cache lockdown program writes the initial value of the sensor input in the internal memory of the I / O control unit 233. For example, for a sensor input that is turned off before the start of the image forming process, data indicating that fact is written to a corresponding address.

Then, the image forming program is activated to simulate the image forming process (S604).
Here, in the present embodiment, the transport system of the image forming apparatus 1 has a configuration as shown in FIG. That is, the sheet feeding unit 120 has two sheet feeding trays of a first stage and a second stage, and the sheets stored in the first stage of the sheet feeding tray are carried out by the single-stage sheet feeding roller 801. Is detected by the single-stage paper feed sensor 802.

  Similarly, the sheet stored in the second-stage paper feed tray is detected by the two-stage paper feed sensor 804 to be carried out by the two-stage paper feed roller 803, and then passes through the two-stage vertical conveyance roller 805. Is detected by the two-stage vertical conveyance sensor 806. The paper set on the manual feed tray 121 is carried out by the multi-hand feed roller 807.

  The timing sensor 808 detects the head of the paper being conveyed. The timing roller 809 conveys the paper in synchronization with the secondary transfer timing. The secondary transfer roller 114 secondary-transfers the toner image onto paper. The fixing loop sensor 810 detects the size of a loop formed by the sheet on the sheet conveyance path from the secondary transfer roller 114 to the fixing device 115.

  The fixing roller 811 thermally fixes the toner image on the paper. The sheet fed by the pre-discharge roller 812 to the discharge port is detected by a discharge sensor 813. The paper discharge roller 814 discharges the paper outside the machine. ADU (Automatic Duplexing Unit) transport rollers 815, 816, 817 and 818 transport the paper so that the toner image is secondarily transferred to the back side of the paper during duplex printing.

  Returning to FIG. 6, when the cache lockdown program starts the image forming program, the image forming program outputs a control output in accordance with the image forming instruction, for example, to start the single-stage paper feed roller 801. This control output is cut off by the I / O control unit 233, written into the internal memory of the I / O control unit 233, and is not output to the mechanical control target unit 232.

  By monitoring the internal memory of the I / O control unit 233, the timing at which the image forming program performs control output can be known, and the cache lockdown program may be operated using this control output timing. . In the present embodiment, the cache lockdown program counts the control cycle of the image forming program and waits for the timing when the paper feed sensor 801 is normally turned on.

When it is time to turn on the paper feed sensor 801 (S605: YES), the cache lockdown program sends the paper feed sensor 801 to the address corresponding to the register of the paper feed sensor 801 in the internal memory of the I / O control unit 233. By setting a bit indicating that the paper feed sensor has been turned on, it is simulated that the paper feed sensor 801 has been turned on (S606).
Next, in the same manner as above, when the timing of the timing sensor 808 comes (S607: YES), the cache lockdown program sets the corresponding bit of the address corresponding to the register of the timing sensor 808, and The turning on of 808 is simulated (S608).

After the timing sensor 808 is turned on, the image processing program outputs a control output for activating the timing roller 809. This control output is also cut off by the I / O control unit 233, and the motor or clutch for driving the timing roller 809 does not actually operate.
The image forming program further estimates the rear end position of the sheet from the ON timing of the timing sensor 808 and, when determining that the rear end of the sheet has passed the stop position of the first-stage paper feed roller 801, sets the one-stage paper feed roller 801 to Output control output to stop. The cache lock-down program simulates turning off the first-stage paper feed sensor 802 when it is time to turn off the paper feed sensor 802 (S609: YES) (S610). Accordingly, the image forming program determines that the rear end of the sheet has passed the detection position of the first-stage sheet feed sensor 802.

When the timing of turning off the timing sensor 808 is reached (S611: YES), the cache lock-down program simulates turning off the timing sensor 808 (S612). Accordingly, the image forming program determines that the trailing edge of the sheet has passed the detection position of the timing sensor 808.
The image forming program further estimates the trailing edge position of the sheet from the timing at which the timing sensor 808 is turned off, and when it is determined that the trailing edge of the sheet has passed the stop position of the timing roller 809, performs a control output to stop the timing roller 809. .

Thereafter, after the same processing is repeated, the cache lockdown program turns on the discharge sensor 813 in a simulated manner when the discharge sensor 813 is turned on (S613: YES) (S614). Accordingly, the image forming program determines that the leading edge of the sheet has reached the detection position of the sheet ejection sensor 813.
The image forming program estimates the leading end position of the sheet from the ON timing of the sheet ejection sensor 813, and performs a control output to stop the timing roller 809 when determining that the leading end of the sheet has passed the stop position of the sheet ejection roller 814. The cache lock-down program simulates turning off the paper ejection sensor 813 when it is time to turn off the paper ejection sensor 813 (S615: YES) (S616). Accordingly, the image forming program determines that the rear end of the sheet has passed the detection position of the sheet discharge sensor 813.

The image forming program further estimates the rear end position of the sheet from the off-timing of the sheet discharge sensor 813, and, when determining that the rear end of the sheet has passed the stop position of the sheet discharge roller 814, stops the sheet discharge roller 814. Perform output.
Thereafter, the cache lockdown program sets the I / O control unit 233 to the normal mode (S617), and ends the processing.

According to this configuration, the image forming process is simulated without actually performing the image forming, and the execution position corresponding to the mode information of the image forming program, that is, the position necessary for the actual execution of the image forming program is determined. It can be stored in the cache memory 203.
[4] Modifications Although the present invention has been described based on the embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and the following modifications can be made. .
(4-1) In the above-described embodiment, a case has been described in which all the control output during the simulation execution is used and the sensor input is simulated using the I / O control unit 233, but the present invention is not limited to this. Needless to say, the following may be used instead.

  As shown in FIG. 9, the image forming apparatus 1 includes a drive motor 900 for rotating and driving a single-stage paper feed roller 801, a timing roller 809, and a paper discharge roller 814. A single-stage paper feed clutch 901, a timing clutch 902, and a paper discharge clutch 903 are provided on a path for transmitting a driving force from the drive motor 900 to the single-stage paper feed roller 801, the timing roller 809, and the paper discharge roller 814, respectively. , And transmits or cuts a driving force from the driving motor 900 to each roller.

Therefore, even if the control output to the drive motor 900 is not interrupted, the image processing can be simulated by disconnecting the first-stage paper feed clutch 901, the timing clutch 902, and the paper discharge clutch 903.
FIG. 10 is an example of a timing chart at the time of the simulation execution. If the cache lockdown program has previously disconnected each clutch during the simulation execution, as shown in FIG. 10, even if the image processing program turns on the control output to connect the single-stage paper feed clutch 901, The driving force of the driving motor 900 is not transmitted to the single-stage paper feeding roller 801 because the driving force is cut by the I / O control unit 233.

  Next, the cache lockdown program sequentially simulates turning on the paper feed sensor 802 and the timing sensor 808. As a result, even if the image forming program sequentially detects the ON state of the sheet feed sensor 802 and the timing sensor 808 and turns on the control output to connect the timing clutch 902, the image forming program is disconnected by the I / O control unit 233. Therefore, the driving force of the driving motor 900 is not transmitted to the timing roller 809.

  Further, in the image forming program, at the timing of connecting the timing clutch 902, the control output is temporarily turned off to stop the sheet conveyance and wait for the secondary transfer timing, so that the first-stage paper feed clutch 901 is disconnected. Thereafter, the control output for connecting the first-stage paper feed clutch 901 is turned on in accordance with the secondary transfer timing, and further, after the rear end of the sheet passes through the first-stage paper feed roller 801, the first-stage paper feed clutch 901 is connected. Turn off the control output.

  The cache lockdown program turns off the single-stage paper feed sensor to simulate that the trailing edge of the paper has passed the detection position of the single-stage paper feed sensor 901. In this embodiment, when the one-stage paper feed sensor is turned off, the image forming program turns on the control output for connecting the paper discharge clutch, but this on-timing differs depending on the configuration of the image forming apparatus. Is also good.

Thereafter, the cache lockdown program simulates turning on the paper ejection sensor 813. When the cache lockdown program further simulates the turning off of the timing sensor 808, the image forming program turns off the control output to disconnect the timing clutch 902.
Further, after a lapse of a predetermined time, the cache lockdown program turns off the sensor input to simulate that the trailing edge of the sheet has passed the detection position of the sheet ejection sensor 813. In response to this, the image forming program outputs a control output for disconnecting the discharge clutch 903 in order to stop the discharge roller 814.

Even in this case, the image forming program can be simulated without actually operating the mechanical control target unit 232.
(4-2) In the above-described embodiment, the operation for simulating the image forming process mainly on the transport system has been described. However, it is needless to say that the present invention is not limited to this. It is necessary to simulate parts other than the system.

For example, the imaging unit 111 includes a photosensitive drum, a charging device, an exposing device, a developing device, a primary transfer roller, and a cleaner for primary transfer of the YMCK color toner image to the image forming position of the intermediate transfer belt 113, respectively. Have.
During the actual image formation, the image forming program uniformly charges the outer peripheral surface of the photosensitive drum with the charging device while rotating and driving the photosensitive drum, forms an electrostatic latent image with the exposure device, and forms the electrostatic latent image with the developing device. The electrostatic latent image is converted to a toner image and electrostatically transferred to an intermediate transfer belt by a primary transfer roller. After the primary transfer, the toner remaining on the outer peripheral surface of the photosensitive drum is removed by a cleaner. The cleaner also removes residual charges by static elimination exposure.

  The transfer scheduled area on the intermediate transfer belt 113, which is the primary transfer destination of the toner image, differs depending on the color mode specified in the image forming process. The image forming program determines the timing at which control output to the charging device, the exposure device, the developing device, the primary transfer roller, and the cleaner is performed so that the YMCK color toner image is transferred to the transfer scheduled area on the intermediate transfer belt 113. It is managed as formation position information.

Therefore, in order for the cache lockdown program to simulate various sensor inputs at appropriate timing, the control cycle of the image forming program may be counted or image forming position information managed by the image forming program may be referred to.
In this way, the image forming process can be simulated for the imaging unit 111 as well.
(4-3) In the above embodiment, the case where the control output is cut off using the I / O control unit 233 to simulate the sensor input has been described as an example, but it goes without saying that the present invention is not limited to this. Alternatively, the simulation execution may be performed only by software processing. For example, at the time of the simulation execution, in addition to executing all the codes of the image forming program executed at the time of the actual execution, a code for interrupting the control output and simulating the sensor input may be executed. By doing so, all the code at the time of the actual execution is stored in the cache memory 203, so that real-time performance at the time of the actual execution can be guaranteed.
(4-4) In the above embodiment, the case where the CPU 200 includes the two cores 201 and 202 has been described as an example. However, it is needless to say that the present invention is not limited to this, and the CPU 200 is a so-called single core. Alternatively, three or more cores may be provided. Further, when three or more cores are provided, the effect of the present invention is the same regardless of which processing is allocated to which core.
(4-5) In the above embodiment, the case where the image forming apparatus is a tandem type color printer has been described as an example. However, it is needless to say that the present invention is not limited to this. It may be a monochrome printer. Further, the same effects can be obtained by applying the present invention to a single-function machine such as a copying machine having a scanner, a facsimile machine having a communication function, or a multi-function peripheral (MFP) having both of these functions. Can be obtained.

  INDUSTRIAL APPLICABILITY The image forming apparatus according to the present invention is useful as an apparatus that guarantees real-time performance when a cache memory is shared between real-time processing and best-effort processing.

1. Image forming apparatus 110 Image forming unit 100 Control unit 200 CPU
201: controller control core 202: mechanical control control core 203: cache memory 231: controller control target unit 232: mechanical control control target unit 233: I / O control unit

Claims (9)

An image forming apparatus that executes an image forming program that requires real-time performance and another program that does not necessarily require real-time performance by sharing one cache memory,
Stopping means for stopping the execution of the other program;
During the execution of the image forming program, an input / output simulation unit that shuts off a control output to be transmitted to each unit of the apparatus and simulates a detection signal of a sensor provided in each unit of the apparatus,
Control cycle changing means for changing a control cycle related to sheet conveyance of the image forming program,
The operation of the other program is stopped by the stopping means, the control output is cut off by the input / output simulating means, the detection signal of the sensor is simulated, and the control cycle is changed by the control cycle changing means. Simulation execution means for simulating the image forming program in a state where the time is shorter than the time,
Prior to the actual execution of the image forming program, a cache lock-down means for executing a cache lock-down of at least an area storing a simulated execution location of the image forming program in a storage area of the cache memory;
After execution of the cache lockdown, a stop release unit for releasing the operation stop of the other program,
An image forming apparatus comprising: a cache lockdown release unit configured to release the cache lockdown after the main execution of the image forming program. With a transport sensor that detects the leading and trailing edges of the paper transported during image formation,
2. The image forming apparatus according to claim 1, wherein the input / output simulation unit causes the image forming program to calculate a sheet conveyance amount by simulating detection signals of a leading edge and a trailing edge of the sheet by the transport sensor. 3. apparatus. Image forming means for forming a toner image;
An image forming sensor that detects an image forming state by the image forming unit,
The image forming apparatus according to claim 1, wherein the input / output simulation unit causes the image forming program to calculate an image forming position by simulating and creating a detection signal of the image forming sensor. A mode information specifying unit that specifies mode information specified in the image forming job;
The image forming apparatus according to claim 1, wherein the simulation execution unit performs the simulation of the image forming program in accordance with the mode information. 5. The image forming apparatus according to claim 4, wherein the mode information is information for designating at least one of a paper feed port, a paper size, a color mode, a printing speed, and a printing surface. 6. The image forming apparatus according to claim 4, wherein the simulation execution unit executes the simulation of the image forming program after the mode information identification unit identifies the mode information. 7. When the image forming program is subsequently executed after the actual execution of the image forming program, the simulated execution after the preceding actual execution and before the subsequent actual execution and the cache lock until the subsequent actual execution is completed. The image forming apparatus according to claim 1, further comprising a prohibition unit that prohibits release of the down state. When the mode information is different between the preceding main execution and the subsequent main execution of the image forming program, the prohibiting unit prohibits neither the simulation execution nor the release of the cache lockdown. The image forming apparatus according to claim 7. 9. The image forming apparatus according to claim 1, wherein the other programs that do not require real-time processing include an image processing program that does not perform mechanical control and a user interface processing program.

Images