JP2019185597A - Memory control device, memory device, image forming apparatus, and program - Google Patents

Abstract

To provide a memory control device capable of increasing power-saving efficiency, while prolonging a service life of a non-volatile memory and to provide a memory device, an image forming apparatus, and a program.SOLUTION: A memory control device 16A includes a control part 40 for performing control for selecting a first mode for holding data written in a cache area of a volatile memory 12C from a non-volatile memory 12B, when a previously set power-saving mode transition condition is satisfied and a value about a service life of the non-volatile memory 12B exceeds a reference value and selecting a second mode for rewriting the data written in the cache area from the non-volatile memory 12B to the non-volatile memory 12B, when the power-saving mode transition condition is satisfied and the value about the service life of the non-volatile memory 12B is the reference value or less.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a memory control device, a memory device, an image forming apparatus, and a program.

  For example, Patent Document 1 describes an image forming apparatus including an HDD (Hard Disk Drive) that operates in a first power state and stops in a second power state that consumes less power than the first power state. Has been. The image forming apparatus shifts from the first power state to the second power state when a predetermined condition is satisfied, and when the person is detected in the second power state, the first power state starts from the second power state. Control to return to the power state. In addition, the image forming apparatus counts the number of times of transition from the second power state to the first power state and stores the number of times in the nonvolatile memory, and compares the number of times with respect to the installation period of the own device with the lifetime information of the HDD. Depending on the result, the frequency of returning from the second power state to the first power state is reduced.

JP2015-208909A

  Incidentally, in recent years, non-volatile memories such as NAND flash memories have been widely used in electronic devices such as image forming apparatuses. In the case of HDDs, it is known that the number of times power is turned on and off greatly affects the lifetime, but in the case of nonvolatile memories, in general, reading (reading) and writing (rather than turning on and off power) The number of accesses to (write) greatly affects the service life. Therefore, in order to extend the life of the nonvolatile memory, data stored in the nonvolatile memory is written to the cache area of the volatile memory and accessed.

  On the other hand, some volatile memories have a self-refresh mode in which the memory itself automatically performs a periodic refresh operation. In the self-refresh mode, a self-refresh operation is executed when the electronic device shifts to the power saving mode. In this case, since the data written in the cache area is always held in the cache area even when the lifetime of the nonvolatile memory is sufficiently long, corresponding power is consumed. There was room for improvement. From these, it is desired to improve the power saving efficiency while extending the life of the nonvolatile memory.

  An object of the present invention is to provide a memory control device, a memory device, an image forming apparatus, and a program capable of improving power saving efficiency while extending the life of a nonvolatile memory.

  In order to achieve the above object, the memory control device according to claim 1, wherein the non-volatile memory device satisfies the predetermined power saving mode transition condition and the nonvolatile memory has a value regarding a lifetime exceeding a reference value. The first mode for holding data written from the volatile memory to the cache area of the volatile memory is selected, the power saving mode transition condition is satisfied, and the value related to the lifetime of the nonvolatile memory is equal to or less than the reference value A control unit that performs control to select a second mode in which the data written from the nonvolatile memory to the cache area is written back to the nonvolatile memory.

  According to a second aspect of the present invention, there is provided the memory control device according to the first aspect of the present invention, wherein the value relating to the lifetime of the nonvolatile memory has a predetermined usable period for an electronic device in which the nonvolatile memory is mounted. The estimated number of accesses in the nonvolatile memory predicted when the nonvolatile memory has passed is used, and the reference value is an allowable number of accesses determined in advance for the nonvolatile memory.

  According to a third aspect of the present invention, there is provided the memory control device according to the second aspect of the present invention, wherein in the second aspect of the invention, the accumulated operation time indicating the accumulation of the operation time of the electronic device and the accumulated operation time during the operation of the electronic device are measured. A second non-volatile memory that stores the number of access measurements in the non-volatile memory to be performed, and the control unit is configured to calculate the estimated access count based on the usable period, the accumulated operation time, and the access measurement count. Is derived.

  According to a fourth aspect of the present invention, there is provided the memory control device according to the first aspect, wherein the value related to the lifetime of the nonvolatile memory is a consumption level with respect to a predetermined lifetime for the nonvolatile memory, and the reference The value is the first ratio of the accumulated operation time that indicates the accumulation of the operation time of the electronic device with respect to the predetermined usable period for the electronic device equipped with the nonvolatile memory.

  According to a fifth aspect of the present invention, in the memory control device according to the first aspect of the present invention, the value related to the lifetime of the nonvolatile memory is accessed with respect to the number of accessible times determined in advance for the nonvolatile memory. The cumulative operation time indicating the cumulative operation time of the electronic device with respect to the predetermined usable period for the electronic device in which the nonvolatile memory is mounted. The first ratio.

  According to a sixth aspect of the present invention, in the memory control device according to the fourth or fifth aspect, the control unit obtains the consumption level from a specific register field provided in the nonvolatile memory.

  According to a seventh aspect of the present invention, in the memory control device according to any one of the fourth to sixth aspects, the reference value is determined in advance for the first ratio and the components constituting the electronic device. The value is determined based on the second ratio of the cumulative number of times of use of the component that is cumulatively measured during the operation of the electronic device with respect to the number of times that the electronic device can be used.

  According to an eighth aspect of the present invention, there is provided the memory control device according to the seventh aspect, wherein the electronic device is composed of a plurality of different types of components, and the reference value is the first ratio, The value is determined based on each of the second ratios obtained for each of the plurality of different types of parts.

  In the memory control device according to claim 9, in the invention according to claim 8, the reference value is a maximum value of each of the first ratio and the second ratio.

  According to a tenth aspect of the present invention, there is provided the memory control device according to the eighth or ninth aspect, wherein the electronic device is an image forming device including an image forming unit and a document reading unit, and the plurality of types are different. The parts are the image forming unit and the document reading unit.

  The memory control device according to an eleventh aspect is the memory control device according to any one of the first to tenth aspects, wherein the control unit sets a predetermined power saving mode return condition after shifting to the second mode. When the above condition is satisfied, control is further performed to write the data from the nonvolatile memory to the cache area.

  According to a twelfth aspect of the present invention, there is provided the memory control device according to any one of the first to eleventh aspects, wherein the first mode uses a refresh circuit provided in the volatile memory. It is a mode.

  According to a thirteenth aspect of the present invention, in the memory control device according to the twelfth aspect of the present invention, the second mode is a mode using a partial array self-refresh function of the self-refresh mode.

  On the other hand, in order to achieve the above object, a memory device according to claim 14 is a non-volatile memory for storing data, a volatile memory provided with a cache area, and any one of claims 1 to 13. And a memory control device that performs control to write the data from the nonvolatile memory to the cache area.

  On the other hand, in order to achieve the above object, an image forming apparatus according to claim 15 is a non-volatile memory that stores data, a volatile memory provided with a cache area, and any one of claims 1 to 13. And a memory control device that performs control to write the data from the nonvolatile memory to the cache area, and image formation that performs image formation using the data written to the cache area. And a section.

  In order to achieve the above object, a program according to claim 16 causes a computer to function as a control unit included in the memory control device according to any one of claims 1 to 13.

  According to the inventions according to claims 1, 14, 15, and 16, the power saving efficiency can be improved while extending the life of the nonvolatile memory.

  According to the invention which concerns on Claim 2, compared with the case where the frequency | count of access prediction and the frequency | count of allowable access are not used, a more suitable mode can be selected.

  According to the invention which concerns on Claim 3, compared with the case where each performance value of accumulation operation time and access measurement frequency is not used, access prediction frequency can be derived | led-out accurately.

  According to the invention of claim 4, it is possible to select a more appropriate mode as compared with the case where the first ratio based on the degree of wear with respect to the lifetime of the nonvolatile memory and the usable period of the electronic device is not used. it can.

  According to the invention according to claim 5, a more appropriate mode is selected as compared with the case where the consumption rate based on the accessible number of times of the nonvolatile memory and the first ratio based on the usable period of the electronic device are not used. can do.

  According to the invention which concerns on Claim 6, compared with the case where it acquires from the memory etc. which were set as another structure, the structure of an apparatus can be simplified more.

  According to the invention which concerns on Claim 7, compared with the case where the 2nd ratio based on the frequency | count which can use the components which comprise an electronic device is not used as a reference value, a more suitable mode can be selected.

  According to the invention which concerns on Claim 8, compared with the case where the kind of component which comprises an electronic device is not considered, a more suitable mode can be selected.

  According to the invention which concerns on Claim 9, a more suitable mode can be selected compared with the case where the maximum value of a 1st ratio and several 2nd ratio is not used.

  According to the tenth aspect of the present invention, when the nonvolatile memory is mounted on the image forming apparatus, it is possible to improve the power saving efficiency while extending the life of the nonvolatile memory.

  According to the eleventh aspect of the present invention, data can be written to the cache area at an appropriate timing as compared with the case where the power saving mode return condition is not considered.

  According to the twelfth aspect of the present invention, the lifetime of the nonvolatile memory can be extended as compared with the case where the data in the cache area of the volatile memory is written back to the nonvolatile memory.

  According to the thirteenth aspect of the present invention, it is possible to improve the power saving efficiency as compared with the case where the partial array self-refresh function in the self-refresh mode is not used.

1 is a block diagram illustrating an example of an electrical configuration of an image forming apparatus according to a first embodiment. 1 is a block diagram illustrating an example of an electrical configuration of a memory device according to a first embodiment. It is a block diagram which shows an example of a functional structure of the memory control apparatus which concerns on 1st Embodiment. It is a flowchart which shows an example of the flow of a process by the memory control program which concerns on 1st Embodiment. It is a flowchart which shows an example of the flow of the 1st mode selection process which concerns on embodiment. It is a flowchart which shows an example of the flow of the 2nd mode selection process which concerns on embodiment. It is a block diagram which shows an example of a functional structure of the memory control apparatus which concerns on 2nd Embodiment. It is a figure which shows an example of the register field which concerns on 2nd Embodiment. It is a flowchart which shows an example of the flow of a process by the memory control program which concerns on 2nd Embodiment. It is a block diagram which shows an example of a functional structure of the memory control apparatus which concerns on 3rd Embodiment. It is a flowchart which shows an example of the flow of a process by the memory control program which concerns on 3rd Embodiment.

  Hereinafter, an example of an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram illustrating an example of an electrical configuration of the image forming apparatus 10 according to the first embodiment.

  As shown in FIG. 1, the image forming apparatus 10 according to the present embodiment includes a main control unit 12A, a storage unit 14, a display unit 18, an operation unit 20, an image forming unit 22, and a document reading unit 24. The communication unit 26 and the memory device 30 are provided. In addition, the memory device 30 according to the present embodiment includes a nonvolatile memory 12B, a volatile memory 12C, and a memory control device 16A. These units are connected to each other via a system bus 28. The image forming apparatus 10 is an example of an electronic device. The electronic apparatus is not limited to the image forming apparatus 10 and may be an information processing apparatus such as a personal computer (PC) or a server computer.

  The image forming apparatus 10 according to the present embodiment has a switchable operation mode between a normal power mode in which the main control unit 12A is in an operating state and a power saving mode in which the main control unit 12A is in a sleep state. Yes.

  When the image forming apparatus 10 satisfies a power saving mode transition condition (described later), the memory control device 16A according to the present embodiment instructs the main control unit 12A to enter the sleep state, and is volatile. The memory 12C is instructed to shift to the self-refresh mode. In response to this instruction, the image forming apparatus 10 shifts to the power saving mode. On the other hand, when the image forming apparatus 10 satisfies a power saving mode return condition (described later), the memory control device 16A instructs the main control unit 12A to return from the sleep state to the operation state, and is volatile. The memory 12C is instructed to cancel the self-refresh mode. In response to this instruction, the image forming apparatus 10 returns from the power saving mode to the normal power mode. Further, the memory control device 16A periodically sends a refresh command to the volatile memory 12C when the image forming apparatus 10 is operating in the normal power mode.

  The main control unit 12A includes a CPU (Central Processing Unit) and controls the overall operation of the image forming apparatus 10. For example, an integrated circuit such as an LSI (Large Scale Integration) or an IC (Integrated Circuit) chip set is used as the main control unit 12A. The integration of the main control unit 12A is not limited to an LSI, and a dedicated circuit or a general-purpose processor may be used.

  As the nonvolatile memory 12B, a flash memory which is an example of a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable ROM), or the like is used. The nonvolatile memory 12B is a storage medium that retains data even when the main power of the image forming apparatus 10 is turned off, but excludes a storage medium that mechanically accesses data such as an HDD. The nonvolatile memory 12B stores various programs and set values necessary for controlling the image forming operation by the image forming apparatus 10 as an example of data.

  As the volatile memory 12C, a DRAM (Dynamic Random Access Memory), an SDRAM (Synchronous DRAM), a DDR SDRAM (Double Data Rate SDRAM), a DDR2 SDRAM, a DDR3 SDRAM, or the like is used as an example of a RAM (Random Access Memory). . The volatile memory 12C functions as a working memory. The volatile memory 12C is a storage medium in which stored data is lost if the volatile memory 12C is left for a certain period of time. For this reason, in the volatile memory 12C, it is necessary to periodically perform a refresh operation in order to continuously hold data. When the image forming apparatus 10 is operating in the normal power mode, the volatile memory 12C performs a refresh operation according to a refresh command periodically sent from the memory control device 16A, and the image forming apparatus 10 is in the power saving mode. In the case of shifting to, the shift to the self-refresh mode is performed in accordance with an instruction from the memory control device 16A, and the self-refresh operation is performed.

  In the self-refresh mode, since the refresh operation is executed in the volatile memory 12C, even when the image forming apparatus 10 shifts to the power saving mode, data held in the volatile memory 12C is not lost. . Since the volatile memory 12C has the self-refresh mode, it is not necessary to send a refresh command from the memory control device 16A, and the main control unit 12A can be shifted to the sleep state, thereby saving power.

  On the other hand, as the storage unit 14, for example, an HDD, an SSD (Solid State Drive), or the like is used. The storage unit 14 stores application programs for executing various processes relating to image formation, print data received from an external PC, and the like.

  For the display unit 18, for example, a liquid crystal display (LCD), an organic EL (Electro Luminescence) display, or the like is used. The display unit 18 integrally has a touch panel. The operation unit 20 is provided with various operation keys such as a numeric keypad and a start key. The display unit 18 and the operation unit 20 receive various instructions from the user of the image forming apparatus 10. These various instructions include, for example, an instruction to start reading a document and an instruction to start copying (copying) a document. The display unit 18 displays various types of information such as a result of processing executed in response to an instruction received from the user and a notification for the processing.

  The document reading unit 24 captures documents one by one on a sheet feeding table of an unillustrated automatic document feeder provided at the top of the image forming apparatus 10 and optically reads the captured documents to obtain image information. . Alternatively, the document reading unit 24 optically reads a document placed on a document table such as a platen glass to obtain image information.

  The image forming unit 22 forms an image based on image information obtained by reading by the document reading unit 24 or image information obtained from an external PC or the like connected via a network on a recording medium such as paper. To do. In the present embodiment, an electrophotographic method is exemplified and described as a method for forming an image, but other methods such as an ink jet method may be adopted.

  When the image forming method is an electrophotographic method, the image forming unit 22 includes a photosensitive drum, a charging unit, an exposure unit, a developing unit, a transfer unit, and a fixing unit. The charging unit applies a voltage to the photosensitive drum to charge the surface of the photosensitive drum. The exposure unit forms an electrostatic latent image on the photosensitive drum by exposing the photosensitive drum charged by the charging unit with light according to image information. The developing unit forms a toner image on the photosensitive drum by developing the electrostatic latent image formed on the photosensitive drum with toner. The transfer unit transfers the toner image formed on the photosensitive drum to a recording medium. The fixing unit fixes the toner image transferred to the recording medium by heating and pressing.

  The communication unit 26 is connected to a network (not shown), and can communicate with an external PC via the network. For example, the Internet, a LAN (Local Area Network), a WAN (Wide Area Network), or the like is applied to this network.

  Next, a specific configuration of the memory device 30 according to the present embodiment will be described with reference to FIG.

  FIG. 2 is a block diagram illustrating an example of an electrical configuration of the memory device 30 according to the first embodiment.

  The nonvolatile memory 12B according to the present embodiment stores data necessary for controlling the image forming operation as described above.

  The volatile memory 12C according to the present embodiment is provided with a cache area and a refresh circuit for performing the refresh operation in the self-refresh mode described above. The volatile memory 12C has a partial array self refresh (hereinafter referred to simply as “PASR”) function in a self refresh mode.

  The PASR function is a function for selectively setting whether to hold data for each of the plurality of storage areas constituting the volatile memory 12C during the self-refresh mode. Whether to set “data retention”, which is a setting for retaining data, or “data non-retention”, which is a setting for not retaining data, is selected by setting a register in the volatile memory 12C. In the storage area set to “data hold”, data is held during the self-refresh mode, and in the storage area set to “data non-hold”, data is not held during the self-refresh mode. In other words, since it is not necessary to execute the self-refresh operation in the storage area in which “data non-retention” is set, further power saving can be achieved as compared with the normal self-refresh mode.

  In the case of the nonvolatile memory 12B, as described above, the number of accesses for reading (reading) and writing (writing) greatly affects the life. Therefore, in order to extend the life of the nonvolatile memory 12B, the data stored in the nonvolatile memory 12B is written in the cache area of the volatile memory 12C, and the cache area is accessed. Thereby, the frequency | count of access to the non-volatile memory 12B is suppressed. On the other hand, in the self-refresh mode, data written in the cache area is always held in the cache area even when the lifetime of the nonvolatile memory 12B is sufficient, so that corresponding power is consumed. Accordingly, it is desired to improve the power saving efficiency while extending the life of the nonvolatile memory 12B.

  The memory control device 16A according to the present embodiment uses the PASR function to selectively switch between a first mode that prioritizes the life of the nonvolatile memory 12B and a second mode that prioritizes power saving of the entire device, The power saving efficiency is improved while extending the life of the nonvolatile memory 12B.

  The memory control device 16A according to the present embodiment includes a CPU 32, a RAM 34, a ROM 36, and a second nonvolatile memory 38.

  The ROM 36 stores a memory control program 36A according to the present embodiment. The memory control program 36A may be installed in advance in the memory control device 16A, for example. The memory control program 36A may be realized by being stored in a non-volatile storage medium or distributed via a network and appropriately installed in the memory control device 16A. As examples of nonvolatile storage media, CD-ROM (Compact Disc Read Only Memory), magneto-optical disk, HDD, DVD-ROM (Digital Versatile Disc Read Only Memory), flash memory, memory card, etc. are assumed. The

  The CPU 32 of the memory control device 16A according to the present embodiment functions as the control unit 40 shown in FIG. 3 by writing the memory control program 36A stored in the ROM 36 into the RAM 34 and executing it.

FIG. 3 is a block diagram illustrating an example of a functional configuration of the memory control device 16A according to the first embodiment.
As illustrated in FIG. 3, the CPU 32 of the memory control device 16 </ b> A according to the present embodiment functions as a control unit 40.

  The control unit 40 according to the present embodiment performs control to write data stored in the nonvolatile memory 12B into the cache area of the volatile memory 12C. Then, the control unit 40 according to the present embodiment selects the first mode when the predetermined power saving mode transition condition is satisfied and the value related to the lifetime of the nonvolatile memory 12B exceeds the reference value, thereby saving When the power mode transition condition is satisfied and the value related to the lifetime of the nonvolatile memory 12B is equal to or less than the reference value, control for selecting the second mode is performed.

  As described above, the first mode is a mode that prioritizes the life of the nonvolatile memory 12B, and is a mode that holds data written from the nonvolatile memory 12B to the cache area of the volatile memory 12C. Specifically, the first mode is a self-refresh mode using a refresh circuit provided in the volatile memory 12C. In the first mode, the data in the cache area of the volatile memory 12C is held as it is, and writing back to the nonvolatile memory 12B is not performed. In this case, the number of accesses to the nonvolatile memory 12B is suppressed, which contributes to extending the life of the nonvolatile memory 12B.

  On the other hand, as described above, the second mode is a mode that prioritizes power saving of the entire apparatus, and is a mode in which data written in the cache area from the nonvolatile memory 12B is written back to the nonvolatile memory 12B. Specifically, the second mode is a mode using the PASR function of the self-refresh mode. In the second mode, data held in the cache area of the volatile memory 12C is written back to the nonvolatile memory 12B, and no data is held in the cache area by setting the PASR function. In this case, it is not necessary to perform a self-refresh operation for the cache area, which contributes to improvement of power saving efficiency in the entire apparatus.

  The power saving mode transition condition is a condition when the image forming apparatus 10 shifts to the power saving mode. As an example, “the case where an operation input by the user is not detected for a certain period of time” or “from the external PC” For example, the print data is not received for a certain period of time.

  In addition, the value related to the lifetime of the nonvolatile memory 12B is, for example, the predicted number of accesses in the nonvolatile memory 12B that is predicted when a predetermined usable period for the image forming apparatus 10 has elapsed. The usable period is a period that represents a life expected in advance for the image forming apparatus 10, and is determined based on, for example, a result of a life test performed by a manufacturer or the like. Further, as will be described later, the predicted access count is calculated by the control unit 40 using a usable period or the like. On the other hand, the reference value is, for example, an allowable number of accesses predetermined for the nonvolatile memory 12B (hereinafter referred to as “allowable access number”). This allowable access count is an allowable read and write access count assumed in advance for the nonvolatile memory 12B, and is determined based on, for example, a result of a life test performed by a manufacturer or the like.

  The second non-volatile memory 38 according to the present embodiment stores the usable period and the allowable access count, the accumulated operation time indicating the accumulated time during which the image forming apparatus 10 is operated, and the image forming apparatus 10. The number of access measurements in the nonvolatile memory 12B that is accumulated and measured during operation is stored. As an example, this accumulated operation time is indicated as the accumulation of the operation time from the time when the image forming apparatus 10 is first started after being installed in a predetermined use place until this time, for example, the most recent power saving mode transition time. It is. The access measurement count is indicated as an accumulation of the number of times that the read / write access is actually performed in the nonvolatile memory 12B while the image forming apparatus 10 is operating. Each of the accumulated operation time and the number of times of access measurement is continuously measured even when the image forming apparatus 10 is stopped (main power is off) or restarted.

The control unit 40 according to the present embodiment measures the accumulated operation time and the number of times of access measurement, and stores the measured value in the second nonvolatile memory 38. Further, the control unit 40 derives the access prediction number based on the usable period, the accumulated operation time, and the access measurement number. Specifically, the usable period T _L, the accumulated operation time T _A, the access number of measurements in the case of the N _M, access prediction number N _P is calculated by equation (1) shown below.

N _P = (T _L / T _A ) × N _M (1)

When using the above equation (1), the control unit 40 according to the present embodiment, satisfies the power saving mode transition condition, and, if the access prediction count N _P exceeds the allowable number of accesses, the first mode is selected satisfies the power saving mode transition condition, and, if the access prediction count N _P is equal to or less than the allowable number of accesses, it performs control to select the second mode. In place of the equation (1), using a previously created data tables, it may derive access prediction count N _P. By controlling the selection of this mode, the power saving efficiency is improved while extending the life of the nonvolatile memory 12B.

  Note that the control unit 40 further performs control of writing data from the nonvolatile memory 12B to the cache area when a predetermined power saving mode return condition is satisfied after the transition to the second mode. The power saving mode return condition is a condition when the image forming apparatus 10 returns from the power saving mode. As an example, “when a user operation input is detected” or “print data is received from an external PC”. And the like.

  Next, the operation of the memory control device 16A according to the first embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing an example of the flow of processing by the memory control program 36A according to the first embodiment.

  First, when the main power supply of the image forming apparatus 10 is turned on, the memory control program 36A is started and the following steps are executed.

  In step 100 of FIG. 4, the control unit 40 starts measuring the cumulative operation time of the image forming apparatus 10 and the number of access measurements in the nonvolatile memory 12B. The measured value obtained at this time is stored in the second nonvolatile memory 38. In addition, when the measurement value until the last time is memorize | stored in the 2nd non-volatile memory 38, the control part 40 continues counting from the measurement value until the last time.

  In step 102, the control unit 40 writes the data stored in the nonvolatile memory 12B to the cache area of the volatile memory 12C. In this case, since data is read from the nonvolatile memory 12B, this read is also counted as the number of times of access measurement.

  In step 104, the control unit 40 puts the main control unit 12A into an operating state and puts the image forming apparatus 10 into the normal power mode. In this normal power mode, the cache area of the volatile memory 12C is accessed. For example, the image forming unit 22 included in the image forming apparatus 10 forms an image using data written in the cache area. However, when writing some important data, direct writing may be performed on the nonvolatile memory 12B. The writing at this time is also counted as the number of times of access measurement. In this normal power mode, as described above, the refresh operation of the volatile memory 12C is executed in response to the refresh command periodically sent from the memory control device 16A to the volatile memory 12C.

  In step 106, the control unit 40 determines whether or not the image forming apparatus 10 satisfies the power saving mode transition condition. If it is determined that the power saving mode transition condition is satisfied (in the case of an affirmative determination), the process proceeds to step 108. If it is determined that the power saving mode transition condition is not satisfied (in the case of a negative determination), the process proceeds to step 118. The power saving mode transition condition is, for example, a condition such as “when an operation input by the user is not detected for a certain period of time” as described above.

  In step 108, the control unit 40 applies the usable period, the accumulated operation time, and the access measurement count stored in the second nonvolatile memory 38 to the above-described equation (1), and calculates the access prediction count. .

  In step 110, the control unit 40 determines whether or not the predicted access count calculated in step 108 exceeds the allowable access count. When it is determined that the predicted access count exceeds the allowable access count (in the case of an affirmative determination), the process proceeds to step 112 and the first mode selection process shown in FIG. 5 is executed. On the other hand, when it is determined that the predicted access count is equal to or less than the allowable access count (in the case of negative determination), the process proceeds to step 114 and the second mode selection process shown in FIG. 6 is executed. The allowable access count is stored in the second nonvolatile memory 38.

  FIG. 5 is a flowchart showing an example of the flow of the first mode selection process according to the present embodiment.

  In step 120 of FIG. 5, the control unit 40 instructs the volatile memory 12C to shift to the self-refresh mode while retaining the data in the cache area. At this time, the control unit 40 instructs the main control unit 12A to shift to the sleep state, and shifts the image forming apparatus 10 to the power saving mode.

  In step 122, the control unit 40 determines whether or not the image forming apparatus 10 satisfies the power saving mode return condition. When it is determined that the power saving mode return condition is satisfied (in the case of an affirmative determination), the process proceeds to step 124. When it is determined that the power saving mode return condition is not satisfied (in the case of a negative determination), the process waits in step 122. The power saving mode return condition is, for example, a condition such as “when an operation input by the user is detected” as described above.

  In step 124, the control unit 40 instructs the volatile memory 12C to cancel the self-refresh mode, and returns to step 116 in FIG.

  FIG. 6 is a flowchart showing an example of the flow of the second mode selection process according to the present embodiment.

  In step 130 of FIG. 6, the control unit 40 writes the data held in the cache area of the volatile memory 12C back to the nonvolatile memory 12B. In this case, since data is written to the non-volatile memory 12B, this writing is also counted as the number of times of access measurement.

  In step 132, the control unit 40 uses the PASR function of the volatile memory 12C to set the cache area to “data not held” so as not to hold the data in the cache area.

  In step 134, the control unit 40 instructs the volatile memory 12C to shift to the self-refresh mode. At this time, the control unit 40 instructs the main control unit 12A to shift to the sleep state, and shifts the image forming apparatus 10 to the power saving mode.

  In step 136, the control unit 40 determines whether or not the image forming apparatus 10 satisfies the power saving mode return condition. If it is determined that the power saving mode return condition is satisfied (in the case of an affirmative determination), the process proceeds to step 138. If it is determined that the power saving mode return condition is not satisfied (in the case of a negative determination), the process stands by in step 136.

  In step 138, the control unit 40 instructs the volatile memory 12C to cancel the self-refresh mode.

  In step 140, the control unit 40 sets the cache area to “data hold” by using the PASR function of the volatile memory 12C, and makes it possible to hold data in the cache area.

  In step 142, the control unit 40 writes the data stored in the nonvolatile memory 12B to the cache area of the volatile memory 12C, and returns to step 116 in FIG. In this case, since data is read from the nonvolatile memory 12B, this read is also counted as the number of times of access measurement.

  Next, in step 116 in FIG. 4, the control unit 40 instructs the main control unit 12 </ b> A to shift to the operation state and returns the image forming apparatus 10 to the normal power mode.

  In step 118, the control unit 40 determines whether or not the main power supply of the image forming apparatus 10 is turned off. When it is determined that the main power supply is not turned off (in the case of negative determination), the process returns to step 106, and when it is determined that the main power supply is turned off (in the case of positive determination), a series of processing by the memory control program 36A is terminated. To do.

  In summary, in the first mode in which the life of the nonvolatile memory 12B is prioritized, the data held in the cache area of the volatile memory 12C is transferred to the nonvolatile memory 12B when the image forming apparatus 10 shifts to the power saving mode. Without writing back, the volatile memory 12C is shifted to the self-refresh mode. When the image forming apparatus 10 returns to the power saving mode, the volatile memory 12C is returned from the self-refresh mode. In this case, data is not read from the nonvolatile memory 12B because the data is held in the cache area of the volatile memory 12C.

  On the other hand, in the second mode in which power saving of the entire apparatus is prioritized, when the image forming apparatus 10 shifts to the power saving mode, data stored in the cache area of the volatile memory 12C is written back to the nonvolatile memory 12B. By setting the PASR function, the volatile memory 12C is shifted to the self-refresh mode without holding data in the cache area. When the image forming apparatus 10 returns to the power saving mode, the volatile memory 12C is returned from the self-refresh mode. In this case, since data is not held in the cache area of the volatile memory 12C, data is read from the nonvolatile memory 12B and written to the cache area.

  As described above, according to the present embodiment, the power saving efficiency of the entire apparatus is improved while extending the life of the nonvolatile memory 12B.

[Second Embodiment]
In the first embodiment, the mode in which one of the first mode and the second mode is selected based on the result of comparing the predicted access count and the allowable access count has been described. In the present embodiment, either the first mode or the second mode is based on the result of comparing the degree of wear obtained from the nonvolatile memory 12B and the first ratio of the cumulative operation time with respect to the usable period of the image forming apparatus 10. A mode for selecting the above will be described.

FIG. 7 is a block diagram illustrating an example of a functional configuration of the memory control device 16B according to the second embodiment.
As shown in FIG. 7, the memory control device 16 </ b> B according to the present embodiment includes a control unit 42. In addition, the same code | symbol is attached | subjected to the component which has the same function as 16 A of memory control apparatuses shown in 1st Embodiment, and repeated description is abbreviate | omitted.

  The nonvolatile memory 12B according to the present embodiment is provided with a specific register field. In this register field, the degree of wear of the nonvolatile memory 12B with respect to a predetermined lifetime for the nonvolatile memory 12B is stored.

  For example, an eMMC (embedded Multi Media Card), which is a kind of nonvolatile memory 12B widely used in embedded devices specialized for a specific application, is provided with a register field that stores the degree of wear. Specifically, as an example, as shown in FIG. 8, “DEVICE_LIFE_TIME_EST_TYP_A field” of an extended CSD (Card-Specific Data) register and the like can be mentioned. This consumption level is updated inside the eMMC according to the number of accesses.

  As an example, as illustrated in FIG. 8, the control unit 42 according to the present embodiment obtains the degree of consumption related to the nonvolatile memory 12B from a specific register field provided in the nonvolatile memory 12B.

On the other hand, the second non-volatile memory 38 according to the present embodiment stores a usable period predetermined for the image forming apparatus 10 and an accumulated operation time indicating an accumulated time during which the image forming apparatus 10 is operated. Yes. In this case, the first ratio serving as the reference value is indicated as a ratio of the accumulated operation time to the usable period. For example, when the usable period is T _L and the cumulative operation time is T _A , the first ratio is T _A / T _L.

  The control unit 42 according to the present embodiment selects the first mode in which priority is given to the lifetime of the nonvolatile memory 12B when the wear level acquired from the specific register field provided in the nonvolatile memory 12B exceeds the first ratio. If the consumption level is less than or equal to the first rate, the second mode that gives priority to power saving of the entire apparatus is selected.

Specifically, as an example, usable period _{T L} is 87600 hours (about 10 years), when the cumulative operation time _{T A} is 50000 hours (about 5.7 years), the first _{ratio, T} A / T _L = 50000 / 87600≈0.57 is calculated. When the wear level at this time is 0.3 as an example, the wear level “0.3” is equal to or less than the first ratio “0.57”, and thus the second mode with power saving priority is selected.

In the above description, the register field of the non-volatile memory 12B stores a consumption level for a predetermined lifetime, but the non-volatile memory 12B is accessed for a predetermined accessible number of times. The ratio of the accumulated number of times may be stored as the degree of wear. In this case, as a non-volatile memory 12B, for example, a nonvolatile memory having a controller having a function of measuring the number of times access is made, if the accessible number was N _X times, the actually measured If the number of accesses is N _Y (≦ N _X ), the degree of wear is N _Y / N _X.

  Next, the operation of the memory control device 16B according to the second embodiment will be described with reference to FIG. FIG. 9 is a flowchart showing an example of the flow of processing by the memory control program 36A according to the second embodiment.

  First, when the main power supply of the image forming apparatus 10 is turned on, the memory control program 36A is started and the following steps are executed. Note that the processing of step 150 to step 156 and step 162 to step 168 is the same as the processing of step 100 to step 106 and step 112 to step 118 shown in FIG. Will be omitted, and only step 158 and step 160 will be described.

  In step 158 of FIG. 9, as an example, the control unit 42 acquires the wear level from a specific register field provided in the nonvolatile memory 12 </ b> B as illustrated in FIG. 8.

  In step 160, the control unit 42 determines whether or not the degree of wear acquired in step 158 exceeds the first ratio. If it is determined that the degree of wear exceeds the first ratio (in the case of affirmative determination), the process proceeds to step 162. If it is determined that the degree of wear is equal to or less than the first ratio (in the case of negative determination), the process proceeds to step 164. . Note that, as described above, the first ratio is calculated based on the usable period and the accumulated operation time for the image forming apparatus 10 stored in the second nonvolatile memory 38.

  As described above, according to the present embodiment, when either the first mode or the second mode is selected, the first is based on the degree of wear obtained from the nonvolatile memory 12B and the usable period of the image forming apparatus 10. Percentage is used. For this reason, it is not necessary to derive the access prediction frequency, and the configuration of the apparatus is simplified.

[Third Embodiment]
In the second embodiment, the mode in which the first ratio of the cumulative operation time to the usable period of the image forming apparatus 10 is used as the reference value has been described. In the present embodiment, a description will be given of a mode in which the reference value is determined using the first ratio and the second ratio of the cumulative number of times of use with respect to the number of times that the parts constituting the image forming apparatus 10 are usable.

FIG. 10 is a block diagram illustrating an example of a functional configuration of the memory control device 16C according to the third embodiment.
As illustrated in FIG. 10, the memory control device 16 </ b> C according to the present embodiment includes a control unit 44. In addition, the same code | symbol is attached | subjected to the component which has the same function as 16 A of memory control apparatuses shown in 1st Embodiment, and repeated description is abbreviate | omitted.

  As an example, as shown in FIG. 8, the control unit 44 according to the present embodiment acquires the consumption level related to the nonvolatile memory 12B from a specific register field provided in the nonvolatile memory 12B.

  On the other hand, the image forming apparatus 10 is configured by a plurality of different types of parts, and the usable number of times is determined as an example of the specification indicating the lifetime of each part as well as the usable period of the image forming apparatus 10. ing. The components here include the image forming unit 22 and the document reading unit 24 described above.

In the second nonvolatile memory 38 according to the present embodiment, in addition to the usable period and the accumulated operation time of the image forming apparatus 10, the number of usable times determined in advance for the components constituting the image forming apparatus 10, The cumulative use count of the component that is accumulated and measured during the operation of the image forming apparatus 10 is stored. In the present embodiment, the image forming unit 22 is applied as an example of the component. In the case of the image forming unit 22, the usable number of times is the number of times that printing can be assumed in advance, and the cumulative number of times of use is the number of times of printing that is accumulated and measured. As an example, the second ratio is indicated as a ratio of the cumulative number of times of use to the usable number of times for the image forming unit 22. For example, when the usable count is N _L and the cumulative use count is N _A , the second ratio is N _A / N _L. In this case, as an example, the reference value is determined as the larger one of the first ratio and the second ratio.

Specifically, as an example, when the usable period T _L is 50000 hours and the cumulative operation time T _A is 25000 hours, the first ratio is calculated as T _A / T _L = 25000/50000 = 0.5. The On the other hand, when the usable number N _L is 20000 times and the accumulated use number N _A is 13000 times, the second ratio is calculated as N _A / N _L = 13000/20000 = 0.65. In this case, the reference value is determined to be the second ratio “0.65” that is larger than the first ratio “0.5”. When the wear level at this time is 0.7 as an example, the wear level “0.7” exceeds the second ratio “0.65”, so the first mode with priority on life is selected.

  The second ratio may be calculated for each of a plurality of different types of parts. The image forming unit 22 and the document reading unit 24 are applied as an example of the plurality of different types of components. In the case of the document reading unit 24, the usable number of times is a number of times that can be scanned in advance, and the cumulative number of times of use is the number of times of scanning that is accumulated and measured. In this case, the reference value is determined as the maximum value among the first ratio for the image forming apparatus 10, the second ratio for the image forming unit 22, and the second ratio for the document reading unit 24.

  Next, the operation of the memory control device 16C according to the third embodiment will be described with reference to FIG. FIG. 11 is a flowchart showing an example of the flow of processing by the memory control program 36A according to the third embodiment.

  First, when the main power supply of the image forming apparatus 10 is turned on, the memory control program 36A is started and the following steps are executed. Note that the processing of Step 170 to Step 176 and Step 182 to Step 188 is the same as the processing of Step 100 to Step 106 and Step 112 to Step 118 shown in FIG. Will be omitted, and only step 178 and step 180 will be described.

  In step 178 of FIG. 11, as an example, the control unit 44 acquires the consumption level from a specific register field provided in the nonvolatile memory 12 </ b> B as illustrated in FIG. 8.

  In step 180, the control unit 44 determines whether or not the wear level acquired in step 178 exceeds the maximum rate. If it is determined that the degree of wear exceeds the maximum ratio (in the case of affirmative determination), the process proceeds to step 182. If it is determined that the degree of wear is equal to or less than the maximum ratio (in the case of negative determination), the process proceeds to step 184. Note that the maximum ratio is a ratio that is the maximum among the first ratio and one or more second ratios. As described above, the second ratio is calculated based on the number of usable times and the cumulative number of times of use for one or more parts stored in the second nonvolatile memory 38.

  As described above, according to the present embodiment, the reference value uses the first ratio based on the usable period of the image forming apparatus 10 and the second ratio based on the number of times that the parts constituting the image forming apparatus 10 can be used. It is determined. For this reason, a more appropriate mode is selected.

  As above, the memory control device, the memory device, and the image forming apparatus have been described as examples. The embodiment may be in the form of a program for causing a computer to execute the functions of the units included in the memory control device. The embodiment may be in the form of a computer-readable storage medium storing this program.

  In the above embodiment, the processing performed by each of the memory control devices 16A, 16B, and 16C may be performed by the main control unit 12A. In this case, the CPU 32, the RAM 34, and the ROM 36 may be unnecessary.

  In addition, the configuration of the memory control device described in the above embodiment is an example, and may be changed according to the situation without departing from the gist.

  Further, the processing flow of the program described in the above embodiment is an example, and unnecessary steps may be deleted, new steps may be added, or the processing order may be changed within a range not departing from the gist. Good.

  Moreover, although the said embodiment demonstrated the case where the process which concerns on embodiment was implement | achieved by a software structure using a computer by running a program, it is not restricted to this. The embodiment may be realized by, for example, a hardware configuration or a combination of a hardware configuration and a software configuration.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12A Main control part 12B Nonvolatile memory 12C Volatile memory 14 Memory | storage parts 16A, 16B, 16C Memory control apparatus 18 Display part 20 Operation part 22 Image formation part 24 Original reading part 26 Communication part 28 System bus 30 Memory device 32 CPU
34 RAM
36 ROM
36A Memory control program 38 Second nonvolatile memory 40, 42, 44 Control unit

Claims (16)

  First data that holds data written from the nonvolatile memory to the cache area of the volatile memory when a predetermined power saving mode transition condition is satisfied and the value related to the lifetime of the nonvolatile memory exceeds a reference value When the mode is selected, the power saving mode transition condition is satisfied, and the value related to the lifetime of the nonvolatile memory is equal to or less than the reference value, the data written from the nonvolatile memory to the cache area is A memory control device including a control unit that performs control for selecting a second mode for writing back to a nonvolatile memory. The value related to the lifetime of the non-volatile memory is an estimated number of accesses in the non-volatile memory that is predicted when a predetermined usable period has elapsed for an electronic device equipped with the non-volatile memory,
The memory control device according to claim 1, wherein the reference value is an allowable number of accesses that is predetermined for the nonvolatile memory. A second non-volatile memory that stores a cumulative operation time indicating a cumulative time of operation of the electronic device, and a number of access measurements in the non-volatile memory that are accumulated and measured during operation of the electronic device;
The memory control device according to claim 2, wherein the control unit derives the predicted access count based on the usable period, the accumulated operation time, and the access measurement count. The value related to the lifetime of the nonvolatile memory is a degree of wear with respect to a predetermined lifetime for the nonvolatile memory,
2. The reference value according to claim 1, wherein the reference value is a first ratio of an accumulated operation time indicating an accumulation of an operation time of the electronic device with respect to a predetermined usable period for the electronic device including the nonvolatile memory. Memory controller. The value related to the lifetime of the nonvolatile memory is a consumption level indicating a ratio of a cumulative number of times access is performed to a predetermined number of accessible times for the nonvolatile memory,
2. The reference value according to claim 1, wherein the reference value is a first ratio of an accumulated operation time indicating an accumulation of an operation time of the electronic device with respect to a predetermined usable period for the electronic device including the nonvolatile memory. Memory controller.   The memory control device according to claim 4, wherein the control unit acquires the consumption level from a specific register field provided in the nonvolatile memory.   The reference value is a second of the first ratio and the cumulative use count of the component that is cumulatively measured during the operation of the electronic device with respect to a predetermined usable count for the components constituting the electronic device. The memory control device according to claim 4, wherein the memory control device is a value determined based on the ratio. The electronic device is composed of a plurality of different types of parts,
The memory control device according to claim 7, wherein the reference value is a value determined based on the first ratio and each of the second ratios obtained for each of the plurality of different types of components.   The memory control device according to claim 8, wherein the reference value is a maximum value of each of the first ratio and the second ratio. The electronic device is an image forming apparatus including an image forming unit and a document reading unit,
The memory control device according to claim 8, wherein the plurality of different types of components are the image forming unit and the document reading unit.   The control unit according to claim 1, further comprising a control for writing the data from the nonvolatile memory to the cache area when a predetermined power saving mode return condition is satisfied after the transition to the second mode. The memory control device according to any one of the above.   The memory control device according to claim 1, wherein the first mode is a self-refresh mode using a refresh circuit provided in the volatile memory.   The memory control device according to claim 12, wherein the second mode is a mode using a partial array self-refresh function of the self-refresh mode. Non-volatile memory for storing data;
Volatile memory with a cache area;
The memory control device according to claim 1, wherein the memory control device performs control to write the data from the nonvolatile memory to the cache area;
A memory device. Non-volatile memory for storing data;
Volatile memory with a cache area;
The memory control device according to claim 1, wherein the memory control device performs control to write the data from the nonvolatile memory to the cache area;
An image forming unit that forms an image using the data written in the cache area;
An image forming apparatus.   The program for functioning a computer as a control part with which the memory control apparatus of any one of Claims 1-13 is provided.