JP2014215738A - Memory management device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily achieve the reduction of power consumption when a power saving mode is executed.SOLUTION: A memory management device 7 includes: a power supply part 2; a mode execution part 11 for selectively executing a normal mode and a power saving mode for more reducing power consumption than the normal mode; a volatile first storage part 13 having a predetermined first bus width; a volatile second storage part 14 having a second bus width having the smaller number of bits than the first bus width; a storage control part 16 for allowing the second storage part 14 to store necessary storage information which should be stored while the power saving mode is executed by the mode execution part 11; and a power supply control part 15 for switching the supply or interruption of a power supply voltage from the power source part 2 to the first storage part 13 and the second storage part 14. The power supply control part 15 supplies the power supply voltage to the second storage part 14, and interrupts the supply of the power supply voltage to the first storage part 13 while the power saving mode is executed by the mode execution part 11.

Description

  The present invention relates to a memory management apparatus and an image forming apparatus, and more particularly to a technique for reducing power consumption when executing a power saving mode.

  2. Description of the Related Art Conventionally, an image forming apparatus such as a copier or a printer that can switch between a normal mode and a power saving mode that suppresses power consumption compared to the normal mode is known. In addition, against the background of increasing interest in energy problems and environmental problems in recent years, there is a further demand for reduction of power consumption during the power saving mode.

  The image forming apparatus may include a plurality of RAMs for program execution and the like, and program data may be stored in each RAM during normal operation. In such an image forming apparatus, it is desired to achieve both proper retention of data stored in each RAM and reliable reduction in power consumption when shifting to the power saving mode. Was difficult.

  Therefore, for example, Patent Document 1 below includes a plurality of RAMs (DRAMs) capable of performing self-refresh, and among the plurality of RAMs, power is supplied to some of the RAMs in the power saving mode, An electronic device that does not supply power to the RAM in the power saving mode is described. In this electronic device, for example, a program that executes display control of the user interface in response to an operation on the user interface is held in the power saving mode in order to quickly respond to a user request when returning to the normal operation mode. By moving the power program to the RAM on the power supply side in the power saving mode and holding it, the program stored in each RAM can be appropriately retained and reliably reduced in power consumption.

  In general, an image forming apparatus uses a DRAM having a small bus width such as 8 bits or 16 bits. For this reason, in the image forming apparatus, in order to improve the data amount per access, a plurality of DRAMs are arranged in parallel to form a storage unit having a 32-bit or 64-bit bus width.

  Specifically, for example, as shown in FIG. 8, the image forming apparatus 9 includes two storage units 92 and 93 in which four DRAMs each having an 8-bit bus width are arranged in parallel, and two storage units 92 and 93. And an ASIC 94 for accessing the system. The ASIC 94 accesses the four DRAMs provided in the storage unit 92 or the storage unit 93 simultaneously using data of 32 bits per access.

JP 2011-59937 A

  However, the image forming apparatus configured as shown in FIG. 8 is applied with the technology of the electronic device described in Patent Document 1, and is configured to supply power only to the storage unit 92 when the power saving mode is executed, for example. In this case, even when the amount of data such as a program to be held during execution of the power saving mode is equal to or less than the storage capacity of one DRAM provided in the storage unit 92, for example, during execution of the power saving mode, It is necessary to supply power to the four DRAMs provided in the storage unit 92. For this reason, there is a possibility that the power supplied to the three DRAMs provided in the storage unit 92 is wasted during execution of the power saving mode.

  The present invention has been made in view of such circumstances, and provides a memory management device and an image forming apparatus that can easily realize a reduction in power consumption when the power saving mode is executed. For the purpose.

  A memory management device according to the present invention alternatively includes a power supply unit that generates a power supply voltage, a normal mode in which power consumption is set to a predetermined power, and a power saving mode in which the power consumption is reduced compared to the normal mode. A mode execution unit to execute, a volatile first storage unit having a predetermined first bus width, and a volatile second storage unit having a second bus width with a smaller number of bits than the first bus width A storage control unit that stores in the second storage unit essential holding information that needs to be held while the power saving mode is being executed by the mode execution unit, and the first storage unit and the storage unit from the power supply unit A power supply control unit that switches between supply and interruption of the power supply voltage to the second storage unit, and the power supply control unit, when the power saving mode is executed by the mode execution unit, the second storage unit Said electric By supplying a voltage to cut off the supply of the power supply voltage to the first storage unit.

  According to this configuration, since the number of bits of the bus width of the second storage unit is smaller than the number of bits of the bus width of the first storage unit, the second storage unit is configured to be smaller than the first storage unit. It is easy to reduce the power consumption of the second storage unit than the power consumption of the first storage unit. In addition, while the power saving mode is being executed by the mode execution unit, the power supply voltage is supplied to the second storage unit, the supply of the power supply voltage to the first storage unit is shut off, and the essential holding information is stored in the second storage unit. Remembered.

  That is, as in the prior art, a plurality of volatile storage units having the same bus width are provided, and a power supply voltage is supplied only to a certain storage unit while the power saving mode is being executed, and the essential storage information is stored in the storage unit. Compared to the case of storing the information in the storage unit, it is easy to reduce the configuration of the storage unit for storing the essential holding information, and the power consumption when the power saving mode is executed by the mode execution unit can be reduced. It can be easily realized.

  In addition, the storage control unit stores the essential retention information in the first storage unit while the normal mode is being executed by the mode execution unit, and the mode execution unit changes the normal mode to the power saving mode. When switching to the above, the required storage information stored in the first storage unit is stored in the second storage unit, and the mode execution unit is configured to store the required storage information in the second storage unit. You may comprise so that execution of the said power saving mode may be started.

  According to this configuration, the essential storage information is stored in the first storage unit while the normal mode is being executed by the mode execution unit. For this reason, when it becomes necessary to access the essential holding information when the normal mode is executed by the mode execution unit, the essential holding information can be accessed with the first bus width wider than the second bus width. As a result, the access speed to the mandatory holding information while the normal mode is being executed by the mode execution unit is higher than when the mandatory holding information stored in the second storage unit is accessed with the second bus width. Can be improved.

  The image forming apparatus according to the present invention includes the memory management device and an image forming unit that forms an image on a sheet using information stored in the first storage unit and / or the second storage unit. Prepare.

  According to this configuration, since the above-described memory management device is provided, in the image forming apparatus, it becomes easy to reduce power consumption when the power saving mode is executed by the mode execution unit.

  According to the present invention, it is possible to provide a memory management device and an image forming apparatus that can easily realize reduction of power consumption when the power saving mode is executed.

1 is a schematic structural diagram of a copying machine according to an embodiment of an image forming apparatus of the present invention. 2 is a block diagram showing an electrical configuration of a copying machine. FIG. It is a block diagram which shows the structure of a part of memory management apparatus which concerns on one Embodiment of the memory management apparatus of this invention. It is explanatory drawing which shows the relationship between the memory area of a 1st memory part and a 2nd memory | storage part, and the address corresponding to a memory area. It is explanatory drawing which shows the data used when accessing a 1st memory | storage part. It is explanatory drawing which shows the data used when accessing a 2nd memory | storage part. It is a flowchart which shows operation | movement when a mode execution part performs a normal mode and a power saving mode alternatively. It is a block diagram which shows an example of a structure of the conventional memory management apparatus.

  Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic structural diagram of a copying machine 1 according to an embodiment of an image forming apparatus of the present invention. FIG. 2 is a block diagram showing the electrical configuration of the copying machine 1. For example, as shown in FIG. 1, the copying machine 1 includes an operation unit 3, a document reading unit 5, a document feeding unit 6, and a main body unit 100.

  The operation unit 3 includes a display unit 31 for displaying information and an operation key unit 32 for allowing the user to perform various instructions. The display unit 31 is configured by, for example, a liquid crystal display having a touch panel function. The operation key unit 32 includes a start key 33, a power saving key 34, and the like. The start key 33 is provided for inputting an instruction to start the operation of each function of the copying machine 1 such as a copy function and a scanner function. The power saving key 34 is provided for inputting an instruction to switch the operation of the mode execution unit 11 (FIG. 2) described later to the power saving mode.

  The document reading unit 5 includes a scanner unit 51 including an exposure lamp, a CCD (Charge Coupled Device), and the like, and a document table 52 and a document reading slit 53 made of a transparent member such as glass.

  The scanner unit 51 is configured to be movable by a drive unit (not shown). When reading a document placed on the document table 52, the scanner unit 51 is moved along the document surface at a position facing the document table 52 to scan the document. The image data representing the acquired image is output to the control unit 10 (FIG. 2) described later. Further, when reading a document fed by the document feeding unit 6, the document is moved to a position facing the document reading slit 53 and synchronized with the document feeding operation by the document feeding unit 6 via the document reading slit 53. The image of the original is acquired, and the image data is output to the control unit 10 (FIG. 2) described later.

  The document feeding unit 6 includes a document placing unit 61 for placing a document, a document discharge unit 62 for discharging a document whose image has been read, and a document placed on the document placing unit 61. A document transport mechanism 63 that feeds out the sheets one by one and transports them to a position facing the document reading slit 53 and discharges them to the document discharge section 62 is provided.

  The main body unit 100 includes a manual feed tray 460, a plurality of paper feed cassettes 461, a plurality of paper feed rollers 462, and the image forming unit 4.

  The paper feed roller 462 pulls out the paper from the manual feed tray 460 on which the paper is placed and the paper feed cassette 461 in which the paper is stored, and conveys the paper toward the image forming unit 4.

  The image forming unit 4 includes a paper transport unit 41, an optical scanning device 42, a photosensitive drum 43, a developing unit 44, a transfer unit 45, a fixing unit 46, and a discharge unit 8.

  The paper transport unit 41 is provided in a paper transport path in the image forming unit 4 and includes a plurality of transport rollers 413. Each transport roller 413 supplies the paper transported by each paper feed roller 462 to the photosensitive drum 43.

  The optical scanning device 42 outputs laser light based on the image data input to the control unit 10 under the control of the control unit 10 to be described later, and scans the photosensitive drum 43 with this laser light, thereby sensing light. An electrostatic latent image is formed on the body drum 43.

  The developing unit 44 forms a toner image by attaching toner to the electrostatic latent image on the photosensitive drum 43. The transfer unit 45 transfers the toner image on the photosensitive drum 43 to a sheet. The fixing unit 46 heats the sheet on which the toner image is transferred to fix the toner image on the sheet.

  The discharge unit 8 includes discharge rollers 81 and 82, a stack tray 85, and a discharge tray 86. The discharge roller 81 discharges the sheet on which the image is formed to the stack tray 85. The discharge roller 82 discharges the sheet on which the image is formed to the discharge tray 86.

  For example, as shown in FIG. 2, the copying machine 1 further includes a memory management device 7 inside the main body 100. The memory management device 7 includes a power supply unit 2, switches 24, 25 and 26, and a control unit 10.

  The power supply unit 2 converts an AC voltage supplied from an AC power source such as a commercial power source into a DC voltage having a predetermined voltage value by an AC / DC converter (not shown), thereby using a power source voltage used for the operation of the copying machine 1. Is generated.

  Each of the switches 24, 25, and 26 is a switch that is turned on / off (opened / closed) under the control of the mode execution unit 11 described later. When the switch 24 is turned on (closed state), the power supply voltage is supplied from the power supply unit 2 to the image forming unit 4, and when the switch 24 is turned off (opened state), the power supply unit 2 transfers to the image forming unit 4. The supply voltage of is interrupted. When the switch 25 is turned on, the power supply voltage is supplied from the power supply unit 2 to the document reading unit 5, and when the switch 25 is turned off, the supply of power supply voltage from the power supply unit 2 to the document reading unit 5 is cut off. The When the switch 26 is turned on, the power supply voltage is supplied from the power supply unit 2 to the document feeding unit 6. When the switch 26 is turned off, the power supply voltage is supplied from the power supply unit 2 to the document feeding unit 6. Blocked. The operation unit 3 and the control unit 10 are supplied with a power supply voltage from the power supply unit 2 without going through a switch.

  The control unit 10 controls the operation of the entire copying machine 1. The control unit 10 temporarily stores, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, an EEPROM (Electrically Erasable and Programmable Read Only Memory) in which a predetermined control program is stored, and data. It comprises a plurality of DRAMs (Dynamic Random Access Memory) for storing data, a DDR controller for accessing the DRAMs, peripheral circuits thereof and the like.

  The control unit 10 causes the CPU to execute a control program stored in the non-volatile memory, and uses a DDR controller and a peripheral circuit, whereby the mode execution unit 11, the print control unit 12, the power supply control unit 15, and the storage control unit 16 are used. Configure. Further, the control unit 10 uses some of the plurality of DRAMs as the first storage unit 13 and other DRAMs as the second storage unit 14.

  The mode execution unit 11 includes a normal mode in which a power supply voltage is supplied from the power supply unit 2 to the image forming unit 4, the document reading unit 5, and the document feeding unit 6, and the image forming unit 4, the document reading unit 5, The power saving mode in which the power supply voltage of the copying machine 1 is reduced by cutting off the supply of the power supply voltage to the document feeding unit 6 is alternatively executed.

  For example, the mode execution unit 11 executes the normal mode when the power to the copying machine 1 is turned on or when the user operates the operation unit 3. When the mode execution unit 11 starts execution of the normal mode, the switches 24, 25, and 26 are turned on to supply the power supply voltage from the power supply unit 2 to the image forming unit 4, the document reading unit 5, and the document feeding unit 6. .

  The image forming unit 4, the document reading unit 5, and the document feeding unit 6 can operate when a power supply voltage is supplied from the power supply unit 2. As a result, it is possible to cause the document feeding unit 6, the document reading unit 5, and the image forming unit 4 to execute the copy function in accordance with the operation instruction received by the operation unit 3. The copy function is a function of causing the document reading unit 5 to read a document placed on the document table 52 or a document fed by the document feeding unit 6 and executing print processing using the read image data. . Here, the printing process is a process in which the image forming unit 4 forms an image on a sheet and discharges the sheet on which the image is formed.

  When the power supply voltage is supplied to the document feeding unit 6, the document reading unit 5, and the image forming unit 4, the power consumption of the copying machine 1 increases. That is, while the mode execution unit 11 is executing the normal mode, the power consumption of the copying machine 1 is in a preset power range that is greater than the power consumption in the power saving mode.

  On the other hand, the mode execution unit 11 performs any operation of the operation unit 3 when the user operates the power saving key 34 when the normal mode is being executed, or during a predetermined period. If not, the power saving mode is executed. When the mode execution unit 11 starts executing the power saving mode, the mode execution unit 11 turns off the switches 24, 25, and 26, respectively. As a result, the mode execution unit 11 cuts off the supply of power supply voltage from the power supply unit 2 to the image forming unit 4, the document reading unit 5, and the document feeding unit 6, and the power consumption of the copying machine 1 is higher than that in the normal mode. Reduce.

  The print control unit 12 receives a copy function execution instruction input by the user operating the operation unit 3. The copy function execution instruction includes, for example, printing conditions such as designation of the paper size, an instruction to reduce or enlarge the image to be formed, and an instruction to adjust the density of the image to be formed.

  When receiving the copy function execution instruction, the print control unit 12 executes print processing based on the print condition included in the received copy function execution instruction. Specifically, the print control unit 12 causes the document reading unit 5 to read a document when the execution of the printing process is started. Image data acquired by the document reading unit 5 is stored in the first storage unit 13 and / or the second storage unit 14 by the storage control unit 16 described later. Then, the print control unit 12 causes the storage control unit 16 (to be described later) to read and read the image data (information) stored in the first storage unit 13 and / or the second storage unit 14 based on the printing conditions. The processed image data is subjected to editing processing such as reduction / enlargement processing and density adjustment processing. Then, the print control unit 12 causes the image forming unit 4 to form an image represented by the edited image data on a sheet having a size specified by the printing conditions, and discharges the sheet on which the image is formed. Let

  Hereinafter, the first storage unit 13, the second storage unit 14, the power supply control unit 15, and the storage control unit 16 will be described in detail with reference to FIG. FIG. 3 is a block diagram showing a partial configuration of the memory management device 7 according to the embodiment of the memory management device of the present invention. The memory management device 7 further includes two switches SW1 and SW2 in addition to the configuration shown in FIG.

  The first storage unit 13 includes, for example, four DRAMs 13a to 13d each having a bus width of 8 bits. Each of the four DRAMs 13a to 13d has a storage capacity of, for example, 128 megabytes. That is, the first storage unit 13 has a 32-bit bus width (first bus width) and a storage capacity of 512 (= 128 × 4) megabytes.

  The second storage unit 14 includes, for example, one DRAM 14a having a bus width of 8 bits. The DRAM 14a has a storage capacity of 128 megabytes, for example. That is, the second storage unit 14 has an 8-bit bus width (second bus width) smaller than the 32-bit bus width of the first storage unit 13 and a storage capacity of 128 megabytes. .

  The power supply control unit 15 switches between supply and interruption of the power supply voltage from the power supply unit 2 to the first storage unit 13 by controlling on / off of the switch SW <b> 1 provided between the power supply control unit 15 and the first storage unit 13. In addition, the power supply control unit 15 switches on / off of the power supply voltage from the power supply unit 2 to the second storage unit 14 by controlling on / off of the switch SW <b> 2 provided between the power storage unit 14 and the second storage unit 14.

  Specifically, when the normal mode is executed by the mode execution unit 11, the power supply control unit 15 turns on both the switch SW1 and the switch SW2 (closed state), and the first storage unit 13 and the second storage unit 14 is supplied with a power supply voltage. On the other hand, when the power saving mode is executed by the mode execution unit 11, the power supply control unit 15 turns on the switch SW2 to supply the power supply voltage to the second storage unit 14, while turning off the switch SW1 (open state). Thus, the supply of the power supply voltage to the first storage unit 13 is cut off.

  The storage control unit 16 reads data stored in a non-illustrated non-volatile memory provided in the control unit 10. Further, the storage control unit 16 stores (writes) data in the first storage unit 13 and the second storage unit 14. The storage control unit 16 acquires (reads out) data stored in the first storage unit 13 and the second storage unit 14.

  Specifically, while the normal mode is being executed by the mode execution unit 11, the storage control unit 16 stores essential holding data (essential holding information) described later in the first storage unit 13, and the mode execution unit 11 When switching from the normal mode to the power saving mode, the essential storage data stored in the first storage unit 13 is stored in the second storage unit 14.

  The essential retention data indicates data that needs to be retained while the power saving mode is being executed by the mode execution unit 11. For example, in the essential holding data, the normal mode is executed by the mode execution unit 11 such as a control program for displaying the operation screen on the display unit 31 or a control program for causing the print control unit 12 to execute a printing process. If it is, the program data for operating the copying machine 1 according to the operation of the operation unit 3 by the user is included. That is, the essential retained data includes data that needs to be read from the second storage unit 14 and executed quickly when the mode execution unit 11 switches from the power saving mode to the normal mode. Note that the essential holding data is not limited to the program data described above, and may include, for example, data indicating an instruction to execute the previous copy function received by the print control unit 12.

  Hereinafter, an operation in which the storage control unit 16 accesses the first storage unit 13 and the second storage unit 14 will be described with reference to FIGS. 3 to 5. The storage control unit 16 accesses the first storage unit 13 and the second storage unit 14 using a DDR (Double Data Rate) controller 16a and a division module 16b.

  The DDR controller 16a has a bus width of 32 (= 8 × 4) bits corresponding to the total bus width (first bus width) of the four DRAMs 13a to 13d provided in the first storage unit 13 per access. In other words, the first storage unit 13 and the second storage unit 14 are accessed using 32-bit data per access.

  The division module 16b divides the data to be written into the first storage unit 13 and the second storage unit 14, and generates 32-bit data to be written into the first storage unit 13 and the second storage unit 14 by the DDR controller 16a. To do. In addition, the division module 16b is configured such that the first storage unit 13 and the second storage unit 14 are obtained from data acquired by 32 bits per access by accessing the first storage unit 13 and the second storage unit 14 by the DDR controller 16a. The data stored in is acquired, and the acquired data is concatenated.

  FIG. 4 is an explanatory diagram showing the relationship between the storage areas of the first storage unit 13 and the second storage unit 14 and the addresses corresponding to the storage areas. For example, as shown in FIG. 4, addresses from 0x0000 — 0000 to 0x1FFF_FFFF are assigned to the 512 megabyte storage area of the first storage unit 13, and 0x2000 — 0000 is assigned to the 128 megabyte storage area of the second storage unit 14. To 0x27FF_FFFF are assigned.

[Operation of writing data to the first storage unit 13]
For example, when the storage control unit 16 writes (stores) data from the storage area corresponding to the address of 0x0000_0000 in the storage area of the first storage unit 13 to the storage area for 64 bits, the storage control unit 16 writes the data using the division module 16b. The target 64-bit data is divided into two 32-bit data.

  FIG. 5 is an explanatory diagram showing data used when accessing the first storage unit 13. Specifically, as shown in FIG. 5, the division module 16b is configured to write 64-bit data to be written from a storage area corresponding to an address of 0x0000 — 0000 to a 32-bit storage area, and an address of 0x0000 — 0004. Is divided into two 32-bit data, that is, data to be written into a 32-bit storage area.

  The storage control unit 16 causes the DDR controller 16a to write the two 32-bit data divided by the division module 16b to the first storage unit 13, respectively. Specifically, as shown in FIG. 5, the DDR controller 16a uses the data to be written from the storage area corresponding to the address 0x0000_0000 divided by the division module 16b to the storage area for 32 bits. 8-bit data is simultaneously written in each of the four DRAMs 13a to 13d provided in the unit 13. Similarly, the DDR controller 16a uses the data to be written to the storage area for 32 bits from the storage area corresponding to the address of 0x0000_0004 divided by the division module 16b, and simultaneously writes 8-bit data to each of the DRAMs 13a to 13d. Write.

[Operation for Reading Data from First Storage Unit 13]
On the other hand, for example, when the storage control unit 16 reads data stored in the storage area for 64 bits from the storage area corresponding to the address 0x0000_0000 in the storage area of the first storage unit 13, the storage controller 16 uses the DDR controller 16 a. The first storage unit 13 is accessed to acquire data by 32 bits.

  Specifically, as illustrated in FIG. 5, the DDR controller 16 a is provided in the first storage unit 13, that is, the data stored in the storage area for 32 bits from the storage area corresponding to the address of 0x0000 — 0000. Data stored in an 8-bit storage area is simultaneously read from the leading storage area of each of the four DRAMs 13a to 13d, and 32-bit data is output. Similarly, the DDR controller 16a stores data stored in the storage area for 32 bits from the storage area corresponding to the address 0x0000_0004, that is, each of the four DRAMs 13a to 13d provided in the first storage unit 13. The data stored in the storage area for the next 8 bits is read at the same time, and 32-bit data is output.

  Then, the storage control unit 16 causes the division module 16b to acquire the data stored in the first storage unit 13 from the two 32-bit data output from the DDR controller 16a and connect them. Specifically, the dividing module 16b concatenates the two 32-bit data as it is, assuming that the two 32-bit data output by the DDR controller 16a are the data itself stored in the first storage unit 13. To do. As a result, the storage control unit 16 obtains the concatenated 64-bit data as data read from the 64-bit storage area from the storage area corresponding to the address 0x0000_0000 in the storage area of the first storage unit 13. To do.

[Operation for writing data to second storage unit 14]
Further, for example, when the storage control unit 16 writes data from the storage region corresponding to the address 0x2000_0000 in the storage region of the second storage unit 14 to the storage region for 32 bits, the division module 16b performs the write target. Four 32-bit data including 8 bits each of 32-bit data is generated.

  FIG. 6 is an explanatory diagram showing data used when accessing the second storage unit 14. Specifically, as shown in FIG. 6, the division module 16b firstly writes 32-bit data to be written from the storage area corresponding to the address of 0x2000_0000 to the 8-bit storage area, and 0x2000_0004. From the storage area corresponding to the address of 0x2000_0008, the data to be written to the storage area of 8 bits from the storage area corresponding to the address 0x2000_0008, and the storage area corresponding to the address of 0x2000_000c The data is divided into four 8-bit data, that is, data to be written in a storage area for 8 bits. Next, the dividing module 16b generates four 32-bit data by concatenating arbitrary data of 24 bits to each of the 8-bit data divided into four.

  The storage control unit 16 causes each of the four 32-bit data generated by the division module 16b to be written to the second storage unit 14 by the DDR controller 16a. Specifically, as shown in FIG. 6, the DDR controller 16a generates 32-bit data including data to be written from the storage area corresponding to the address 0x2000_0000 generated by the division module 16b to the storage area for 8 bits. Using this, 8-bit data is written to one DRAM 14 a provided in the second storage unit 14. However, since the second storage unit 14 includes only one DRAM 14a, the DDR controller 16a outputs the remaining 24-bit arbitrary data to the second storage unit 14 but cannot write data.

  Similarly, the DDR controller 16a uses the 32-bit data including the data to be written to the 8-bit storage area from the storage area corresponding to the address of 0x2000_0004 generated by the division module 16b, and uses the 8-bit data to the DRAM 14a. 8 bits of data are written to the DRAM 14a using 32 bits of data including data to be written from the storage area corresponding to the address 0x2000_0008 to the storage area of 8 bits, and the storage corresponding to the address 0x2000_000c. 8-bit data is written to the DRAM 14a using 32-bit data including data to be written from the area to the 8-bit storage area.

[Operation for Reading Data from Second Storage Unit 14]
On the other hand, for example, when the storage control unit 16 reads data stored in the storage area for 32 bits from the storage area corresponding to the address of 0x2000_0000 among the storage areas of the second storage unit 14, the DDR controller 16a The second storage unit 14 is accessed and data is acquired 32 bits at a time.

  Specifically, as shown in FIG. 6, the DDR controller 16 a is provided in the data stored in the storage area for 8 bits from the storage area corresponding to the address of 0x2000 — 0000, that is, provided in the second storage unit 14. Read the data stored in the 8-bit storage area from the top storage area of one DRAM 14a, concatenate 24-bit arbitrary data to the read 8-bit data, and then connect the 32-bit data Is output.

  Similarly, the DDR controller 16a stores the data stored in the storage area for 8 bits from the storage area corresponding to the address of 0x2000_0004, that is, the data stored in the storage area for the next 8 bits of the DRAM 14a. Read, concatenate any 24-bit data, and output the concatenated 32-bit data. Further, the DDR controller 16a reads the data stored in the storage area for 8 bits from the storage area corresponding to the address of 0x2000_0008, that is, the data stored in the storage area for the next 8 bits of the DRAM 14a, 24-bit arbitrary data is concatenated, and the concatenated 32-bit data is output. Further, the DDR controller 16a reads the data stored in the storage area for 8 bits from the storage area corresponding to the address of 0x2000_000c, that is, the data stored in the storage area for the next 8 bits of the DRAM 14a, 24-bit arbitrary data is concatenated, and the concatenated 32-bit data is output.

  Then, the storage control unit 16 causes the division module 16b to acquire and link the data stored in the second storage unit 14 from the four 32-bit data output from the DDR controller 16a. Specifically, the dividing module 16b assumes that the leading 8-bit data of each of the four 32-bit data output by the DDR controller 16a is the data stored in the second storage unit 14. First 8-bit data is acquired from each of the four 32-bit data, and the acquired four 8-bit data are concatenated. Thereby, the storage control unit 16 acquires the concatenated 32-bit data as data read from the storage area for 32 bits from the storage area corresponding to the address of 0x2000 — 0000 among the storage areas of the second storage unit 14. To do.

  Hereinafter, an operation when the mode execution unit 11 executes the normal mode and the power saving mode alternatively will be described with reference to FIG. FIG. 7 is a flowchart illustrating an operation when the mode execution unit 11 alternatively executes the normal mode and the power saving mode.

  When the power of the copying machine 1 is turned on by turning on the switch of the power supply unit 2 (not shown), the mode execution unit 11 starts executing the normal mode and turns on the switches 24, 25, and 26. Then, a power supply voltage is supplied from the power supply unit 2 to the image forming unit 4, the document reading unit 5, and the document feeding unit 6 (S1).

  When the normal mode is executed by the mode execution unit 11, the power supply control unit 15 turns on both the switch SW1 and the switch SW2, and supplies the power supply voltage from the power supply unit 2 to the first storage unit 13 and the second storage unit 14. Supply (S2).

  When the power supply voltage is supplied from the power supply unit 2 to the first storage unit 13 and the second storage unit 14, the storage control unit 16 controls the display unit 31 to display various operation screens from the nonvolatile memory, for example. Program data for operating the copier 1 such as a program and a control program for causing the print control unit 12 to execute print processing is read, and the read program data is stored in the first storage unit 13 as essential holding data ( S3).

  When the mode execution unit 11 is executing the normal mode, the user does not operate the power saving key 34 (S4; NO), and the user operates the operation unit 3 within a predetermined period. If not (S5; YES), the storage control unit 16 stores the essential storage data stored in the first storage unit 13 in the second storage unit 14 (S6).

  When the essential storage information is stored in the second storage unit 14, the mode execution unit 11 starts executing the power saving mode, turns off the switches 24, 25, and 26 and turns off the power supply unit 2 to the image forming unit 4. Then, the supply of the power supply voltage to the document reading unit 5 and the document feeding unit 6 is cut off (S7).

  When the power saving mode is executed by the mode execution unit 11, the power supply control unit 15 supplies the power supply voltage to the second storage unit 14 with the switch SW2 turned on, while turning off the switch SW1 to perform the first storage. The supply of power supply voltage to the unit 13 is cut off (S8).

  Thereafter, when the user operates the operation unit 3 (S9; YES), the mode execution unit 11 executes the normal mode instead of the power saving mode, turns on the switches 24, 25, and 26, and turns on the power supply unit. The power supply voltage is supplied from 2 to the image forming unit 4, the document reading unit 5, and the document feeding unit 6 (S10).

  When the normal mode is executed by the mode execution unit 11, the power supply control unit 15 turns on both the switch SW1 and the switch SW2 to turn on the first storage unit 13 and the second storage unit from the power supply unit 2 as in step S2. A power supply voltage is supplied to the unit 14 (S11).

  When the supply of the power supply voltage from the power supply unit 2 to the first storage unit 13 and the second storage unit 14 is started, the storage control unit 16 stores the essential holding data stored in the second storage unit 14 in step S6. Then, it is stored in the first storage unit 13 (S12). After execution of step S12, the processes after step S4 are repeated.

  According to the configuration of the above embodiment, the number of bits of the bus width of the second storage unit 14 is 8 bits, which is smaller than 32 bits that is the number of bits of the bus width of the first storage unit 13. For this reason, it is easy to make the 2nd memory | storage part 14 smaller than the 1st memory | storage part 13, and the power consumption of the 2nd memory | storage part 14 can be reduced rather than the power consumption of the 1st memory | storage part 13. FIG. It becomes easy. In addition, while the power saving mode is being executed by the mode execution unit 11, the power supply voltage is supplied to the second storage unit 14, the supply of the power supply voltage to the first storage unit 13 is cut off, and the essential retained data is stored in the second storage data. It is stored in the storage unit 14.

  That is, as shown in FIG. 8, for example, a plurality of volatile storage units 92 and 93 having the same 32-bit bus width are provided, and a power supply voltage is supplied only to a certain storage unit while the power saving mode is being executed. Therefore, it is easy to downsize the configuration of the storage unit that stores the essential retention data, compared with the case where the essential retention data is stored in the storage unit, and the power saving mode is executed by the mode execution unit 11. It is possible to easily realize a reduction in power consumption during operation.

  Further, according to the configuration of the above-described embodiment, the essential holding data is stored in the first storage unit 13 while the normal mode is being executed by the mode execution unit 11. For this reason, when it becomes necessary to access the essential retained data when the mode execution unit 11 is executing the normal mode, the essential retained data can be accessed 32 bits at a time. As a result, the access speed to the essential retained data while the normal mode is being executed by the mode execution unit 11 is compared to when the mandatory retained data stored in the second storage unit 14 is accessed 8 bits at a time. Can be improved.

  In addition, the structure shown in FIGS. 1-7 in the said embodiment is only an example, and is not the meaning which limits this invention to the said embodiment.

  For example, in the above embodiment, the storage control unit 16 accesses the first storage unit 13 and the second storage unit 14 using 32-bit data per access using the DDR controller 16a and the division module 16b. It was. However, instead of this, the storage control unit 16 uses a DDR controller incorporating a function for performing the same operation as the division module 16b, and uses the 32-bit data per access to store the first storage unit 13 and You may comprise so that the 2nd memory | storage part 14 may be accessed.

  In addition, the storage control unit 16 replaces the program data read from the nonvolatile memory in step S3 (FIG. 7) with the first storage unit 13 as the essential holding data and stores the program data read from the nonvolatile memory. You may comprise so that data may be memorize | stored in the 2nd memory | storage part 14 as essential holding | maintenance data. In accordance with this, the storage controller 16 may be simplified so as not to execute Step S6 and Step S12.

  Further, the image forming apparatus according to the present invention can be applied to a printer apparatus, a facsimile apparatus, a multifunction machine, and the like, in addition to the case where the image forming apparatus is applied to the copying machine 1 described above.

1 Copying machine (image forming device)
2 power supply unit 3 operation unit 4 image forming unit 5 document reading unit 6 document feeding unit 7 memory management device 10 control unit 11 mode execution unit 12 print control unit 13 first storage unit 13a to 13d DRAM
14 Second storage unit 14a DRAM
15 Power Supply Control Unit 16 Storage Control Unit 16a DDR Controller 16b Split Module 24 Switch 25 Switch 26 Switch 31 Display Unit 34 Power Saving Key 100 Main Unit SW1 Switch SW2 Switch

Claims (3)

A power supply for generating a power supply voltage;
A mode execution unit that alternatively executes a normal mode in which power consumption is set to a predetermined power and a power saving mode in which the power consumption is reduced compared to the normal mode;
A volatile first storage unit having a predetermined first bus width;
A volatile second storage unit having a second bus width with fewer bits than the first bus width;
A storage control unit that stores in the second storage unit essential holding information that needs to be held while the power saving mode is being executed by the mode execution unit;
A power supply control unit that switches supply or cutoff of the power supply voltage from the power supply unit to the first storage unit and the second storage unit;
With
The power supply control unit supplies the power supply voltage to the second storage unit and cuts off the supply of the power supply voltage to the first storage unit when the power saving mode is executed by the mode execution unit. Memory management device. The storage control unit stores the essential storage information in the first storage unit while the normal mode is being executed by the mode execution unit, and the mode execution unit switches from the normal mode to the power saving mode. The essential storage information stored in the first storage unit is stored in the second storage unit,
The memory management device according to claim 1, wherein the mode execution unit starts execution of the power saving mode after the essential storage information is stored in the second storage unit. The memory management device according to claim 1 or 2,
An image forming unit that forms an image on a sheet using information stored in the first storage unit and / or the second storage unit;
An image forming apparatus comprising:

Images