JP2013137365A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of improving a power-saving effect without losing data volatilly stored before entering a power-saving state.SOLUTION: When an image forming apparatus shifts from a normal state to a power-saving state, a power supply unit 150 supplies power to a RAM 135 for holding data while stopping supply of power to a RAM 134 for work. Upon shifting from the normal state to the power-saving state, the RAM 134 for work saves data volatilly stored before entering the power-saving state in the RAM 135 for holding data.

Description

  The present invention relates to an image forming apparatus.

  In recent years, demands for power saving have been increasing for image forming apparatuses, and various image forming apparatuses equipped with a power saving mode have been proposed. An image forming apparatus equipped with a power saving mode is disclosed in Patent Document 1, for example.

  An image forming apparatus equipped with a conventional power saving mode normally switches from the normal operation mode to the power saving mode when a certain period of time has passed without the apparatus being used. When the power saving mode is entered, power supply to each part of the apparatus executing the job is cut off, thereby reducing power consumption. When any operation is performed in the power saving mode (for example, when a key provided on the operation panel is pressed), the power saving mode is switched to the normal operation mode, and the power supply to each part of the apparatus is resumed. Is done.

JP 2004-222234 A

  By the way, in the image forming apparatus, when the apparatus is turned on, various program data for executing the job is read from the nonvolatile memory to the volatile memory, and the developed program data (startup image) is stored in the volatile memory. Hold. The volatile memory is used as a work area.

  However, when the normal operation mode is switched to the power saving mode and the power supply to the volatile memory is interrupted, the startup image held in the volatile memory before entering the power saving mode is lost. Therefore, when switching from the power saving mode to the normal operation mode again, it is necessary to start from the process of reading the program data from the non-volatile memory to the volatile memory. In order to eliminate this inconvenience, the power supply to the volatile memory may be continued after entering the power saving mode, but a new inconvenience that the power saving effect is reduced occurs.

  The present invention has been made to solve the above-described problem, and provides an image forming apparatus capable of enhancing the power saving effect without losing data stored in a volatile manner before entering the power saving state. The purpose is to provide.

  In order to achieve the above object, an image forming apparatus of the present invention includes a first volatile memory serving as a work area for developing and executing data, and a second volatile memory having a memory capacity smaller than that of the first volatile memory. And a power supply unit for supplying power to the first volatile memory and the second volatile memory. When the power supply unit shifts from the normal state to the power saving state, the power supply unit supplies power to the second volatile memory while stopping the supply of power to the first volatile memory. When shifting from the normal state to the power saving state, the data stored before entering the power saving state is saved in the second volatile memory. For example, when a certain time has passed without the image forming apparatus being used, or when the image forming apparatus receives an instruction to shift from the normal state to the power saving state, the normal state shifts to the power saving state.

  According to the configuration of the present invention, when the power supply unit shifts from the normal state to the power saving state, the power source unit supplies power to the second volatile memory while stopping the supply of power to the first volatile memory. Therefore, when the state shifts from the normal state to the power saving state, the data stored in the first volatile memory before entering the power saving state is saved in the second volatile memory, thereby entering the power saving state. Thus, the data stored in the first volatile memory is not lost (held in the second volatile memory). Therefore, when returning from the power saving state to the normal state, it is not necessary to read out the data from the non-volatile memory and develop it, and the apparatus can be started up quickly.

  In addition, since the second volatile memory that supplies power in the power saving state has a smaller memory capacity than the first volatile memory, power is supplied to the first volatile memory in the power saving state (power saving). Compared with the case where the data stored in the first volatile memory is kept as it is before entering the state), the power consumption is reduced and the power saving effect is enhanced.

  Further, since the second volatile memory for saving data is inexpensive, an increase in cost can be suppressed.

  In the above configuration, preferably, the second volatile memory does not hold data in a normal state. With this configuration, the memory area of the second volatile memory is an empty area when shifting from the normal state to the power saving state. Therefore, when shifting from the normal state to the power saving state, it is possible to easily secure a memory area for saving data.

  In the above configuration, preferably, the first volatile memory receives data saved in the second volatile memory from the second volatile memory when the normal state is restored from the power saving state. With this configuration, after returning from the power saving state to the normal state, the first volatile memory having a memory capacity larger than that of the second volatile memory becomes the work area, so that the processing speed does not decrease. .

  In the above configuration, it is preferable to further include a processing unit that performs compression processing on data to be saved from the first volatile memory to the second volatile memory. With this configuration, there is a disadvantage that data cannot be saved (memory capacity is insufficient) due to the memory capacity of the second volatile memory being smaller than the memory capacity of the first volatile memory. Generation | occurrence | production can be suppressed.

  As described above, according to the present invention, it is possible to easily obtain an image forming apparatus capable of enhancing the power saving effect without losing the data stored volatilely before entering the power saving state. .

1 is a schematic view of an image forming apparatus according to an embodiment of the present invention. The figure which showed the hardware constitutions of the image forming apparatus shown in FIG. FIG. 3 is a diagram for explaining signals input to a nonvolatile memory mounted in the image forming apparatus shown in FIG. 1 and supplied power. 1 is a diagram for explaining an operation when the image forming apparatus shown in FIG. 1 shifts from a normal state to a power saving state (when returning from a power saving state to a normal state).

  The overall configuration of the image forming apparatus 100 according to an embodiment of the present invention will be described below with reference to FIG.

  The image forming apparatus 100 according to the present embodiment is a multifunction peripheral and can execute a plurality of types of jobs such as copying, printers, scanners, and fax machines. The image forming apparatus 100 includes an operation panel 101, an image reading unit 102, a paper feeding unit 103, a conveyance path 104, an image forming unit 105, a fixing unit 106, and the like.

  The operation panel 101 includes a liquid crystal display unit 11 whose display surface is covered with a touch panel. The liquid crystal display unit 11 displays setting keys (soft keys) for performing various settings, and also displays messages indicating the device status and the like. The operation panel 101 is also provided with a numeric keypad 12 (hard key) for accepting setting instructions that require numerical input, a start key 13 (hard key) for accepting start instructions for executing various jobs, and the like. Yes.

  The image reading unit 102 reads a document and generates image data. Although not shown, the image reading unit 102 is provided with optical system members such as an exposure lamp, a mirror, a lens, and an image sensor. Then, when reading the document placed on the placement reading contact glass 21, the image reading unit 102 irradiates the document with the light of the exposure lamp and A / D converts the output value of the image sensor that receives the reflected light. After that, image data is generated by performing various corrections (such as shading correction) on the data after A / D conversion. Thus, printing can be performed based on the image data obtained by the original reading operation by the image reading unit 102. In addition, image data obtained by a document reading operation by the image reading unit 102 can be accumulated.

  The image reading unit 102 is provided with a document cover 22. When the original is read by the placement reading contact glass 21, the original placed on the placement reading contact glass 21 can be pressed by the original cover 22. The document cover 22 may have a function as a document conveying device. In this case, the manuscript cover 22 can feed manuscripts one by one to the feed reading contact glass 23.

  The paper feed unit 103 has a plurality of cassettes 31 for storing paper P, and supplies the paper P stored in the plurality of cassettes 31 to the conveyance path 104. The paper feed unit 103 is provided with a pickup roller 32 that pulls out the stored paper P, a separation roller pair 33 for suppressing double feeding of the paper P, and the like.

  The conveyance path 104 conveys the paper P inside the apparatus. More specifically, the paper P supplied from the paper supply unit 103 passes through the image forming unit 105 and the fixing unit 106 in this order by the conveyance path 104 and is guided to the discharge tray 41. A plurality of transport roller pairs 42 that transport the paper P are provided in the transport path 104. Further, a registration roller pair 43 is also provided that waits for the paper P in front of the image forming unit 105 and sends the paper P to the image forming unit 105 in time.

  The image forming unit 105 forms a toner image based on the image data, and transfers the toner image onto the paper P. The image forming unit 105 includes a photosensitive drum 51, a charging device 52, an exposure device 53, a developing device 54, a transfer roller 55, a cleaning device 56, and the like.

  As a toner image forming process and a toner image transfer process, first, the photosensitive drum 51 is rotationally driven, and the surface of the photosensitive drum 51 is charged to a predetermined potential by the charging device 52. The exposure device 53 outputs a light beam L based on the image data, and scans and exposes the surface of the photosensitive drum 51. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 51. Subsequently, the developing device 54 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 51 and develops it.

  The transfer roller 55 is in pressure contact with the surface of the photosensitive drum 51. Thereafter, the registration roller pair 43 measures the timing and causes the paper P to enter between the transfer roller 55 and the photosensitive drum 51. At this time, a predetermined voltage is applied to the transfer roller 55. As a result, the toner image on the surface of the photosensitive drum 51 is transferred to the paper P. When the toner image transfer process is finished, the cleaning device 56 removes the toner remaining on the surface of the photosensitive drum 51.

  The fixing unit 106 heats and presses the toner image transferred onto the paper P to fix it. The fixing unit 106 includes a fixing roller 61 having a built-in heat source, and a pressure roller 62 that is pressed against the fixing roller 61. The paper P on which the toner image is transferred is heated and pressed by passing between the fixing roller 61 and the pressure roller 62. As a result, the toner image is fixed on the paper P and printing is completed. The printed paper P is guided to the transport path 104 and is sent to the discharge tray 41 by the transport roller pair 42.

  Next, the hardware configuration of the image forming apparatus 100 will be described with reference to FIG.

  The image forming apparatus 100 includes a main control unit 110 (processing unit), and the main control unit 110 includes a CPU 111 and an image processing unit 112 which are central processing units. The image processing unit 112 includes an ASIC dedicated to image processing, a memory, and the like, and performs various types of image processing such as enlargement / reduction, density conversion, and data format conversion on the image data.

  The main control unit 110 is connected to the operation panel 101, the image reading unit 102, the paper feeding unit 103, the conveyance path 104, the image forming unit 105, the fixing unit 106, and the like. The main control unit 110 performs overall control, image processing control, drive control of a motor that rotates various rotating bodies, and the like based on program data and various data stored in the storage unit 113. The main control unit 110 may be divided into a control unit that performs overall control and image processing control, and a control unit that performs motor control for rotating various rotating bodies.

  The storage unit 113 includes a ROM 131, a RAM 132, an HDD 133, and the like. For example, program data for performing control and calculation of each part of the apparatus is stored in the ROM 131 in a nonvolatile manner. The program data stored in the ROM 131 is read into the RAM 132 and stored in a volatile manner. The RAM 132 will be described later in detail.

  The operation panel 101 connected to the main control unit 110 includes a display control unit 14. The display control unit 14 includes a CPU, an IC, and the like, and when a setting key displayed on the liquid crystal display unit 11 is pressed, the output of the touch panel is received and the coordinates of the pressed position are specified (the pressed setting key is specified). To do). Data indicating the correspondence between the output of the touch panel and the coordinates of the pressed position is stored in, for example, the storage unit 15 (or the storage unit 113). Note that the main control unit 110 may perform display control.

  In addition, the image forming apparatus 100 includes a communication unit 140 connected to the main control unit 110. For example, the communication unit 140 is connected to the external computer 200 via the network NT so that communication is possible. Accordingly, printing can be performed based on the image data transmitted from the computer 200, and the image data obtained by the document reading operation by the image reading unit 102 can be transmitted to the computer 200. Further, a modem or the like may be built in the communication unit 140. In this case, fax communication can be performed with the external fax machine 300 via the network NT such as a telephone line.

  Further, the image forming apparatus 100 includes a power supply unit 150. The power supply unit 150 is connected to a commercial power supply and generates a voltage necessary for operating each unit of the apparatus. And the power supply part 150 supplies electric power to all the parts of each apparatus in a normal state. On the other hand, when the power supply unit 150 shifts from the normal state to the power saving state, a part of the device units (for example, the main control unit 110 and conditions for returning from the power saving state to the normal state are satisfied). The power is supplied only to the return condition detection unit for detecting this, and the supply of power to the other parts is stopped.

  For example, when the apparatus is in use, the main control unit 110 causes the power supply unit 150 to supply power to all parts of each unit of the apparatus and keep the normal state. Furthermore, the main control unit 110 counts the unused time that has elapsed since the use of the device has been completed and the device has not been used. If the unused time is within a certain time, the power to all parts of the device Supply is performed by the power supply unit 150 and the normal state is maintained.

  On the other hand, when the unused time exceeds a certain time, the main control unit 110 causes the power supply unit 150 to supply power to only a part of each unit of the device, and shifts from the normal state to the power saving state. Let Alternatively, the main control unit 110 also receives the instruction to shift from the normal state to the power saving state (for example, when the power saving key provided on the operation panel 101 is pressed). The power supply unit 150 performs power supply to only a part of them, and shifts from the normal state to the power saving state.

  When the main control unit 110 detects that the condition for returning from the power saving state to the normal state is satisfied, the main control unit 110 causes the power supply unit 150 to resume the power supply to all parts of each unit of the apparatus, and from the power saving state to the normal state Return to.

  Note that the main control unit 110 must determine whether or not the condition for returning from the power saving state to the normal state is satisfied after the transition from the normal state to the power saving state. For this reason, even if the main control unit 110 is in a power saving state, it receives power supply from the power supply unit 150 and is partially activated. When the main control unit 110 receives a signal indicating that the condition for returning from the power saving state to the normal state is satisfied in the power saving state, the condition for returning from the power saving state to the normal state is satisfied. It is determined that

  For example, the return condition detection unit outputs a signal indicating that the return condition from the power saving state to the normal state is satisfied to the main control unit 110. For this reason, in the power saving state, power is also supplied from the power supply unit 150 to the return condition detection unit.

  An operation panel 101 is an example of a part corresponding to the return condition detection unit. For example, when the touch panel is touched or a hard key is pressed while the operation panel 101 is in the power saving state, a signal indicating that there has been an operation (the condition for returning from the power saving state to the normal state is satisfied). To the main control unit 110. When receiving a signal from the operation panel 101 in the power saving state, the main control unit 110 returns from the power saving state to the normal state.

  The communication unit 140 also functions as a return condition detection unit. That is, when the communication unit 140 receives data (for example, image data) from an external device such as the computer 200 or the fax machine 300 in the power saving state, the communication unit 140 indicates that the data has been received from the external device (power saving). A signal indicating that the condition for returning from the normal state to the normal state is satisfied) is transmitted to the main control unit 110. Then, when receiving a signal from the communication unit 140 in the power saving state, the main control unit 110 returns from the power saving state to the normal state.

  Furthermore, a sensor for detecting attachment / detachment of the paper cassette 31 and a sensor for detecting opening / closing of the document cover 22 also function as a return condition detection unit. That is, when the main control unit 110 receives a signal that the paper cassette 31 has been attached or detached or the document cover 22 has been opened or closed in the power saving state, the main control unit 110 returns from the power saving state to the normal state.

  Next, the RAM 132 mounted in the image forming apparatus 100 will be described in detail with reference to FIG.

  The RAM 132 includes a work RAM 134 (first volatile memory) and a data holding RAM 135 (second volatile memory) provided separately from the work RAM 134. The work RAM 134 and the data holding RAM 135 are connected to the main control unit 110 via the memory bus MB, and transmit / receive data to / from the main control unit 110. Data is also transmitted and received between the work RAM 134 and the data holding RAM 135.

  These work RAM 134 and data holding RAM 135 have a self-refresh function. For example, the main control unit 110 individually switches the signal levels of the clock enable signals CKE1 and CKE2 in order to cause the work RAM 134 and the data holding RAM 135 to perform self-refresh.

  In addition, the work RAM 134 and the data holding RAM 135 receive power supply from the power supply unit 150 separately. In the following description, the drive voltage of the work RAM 134 is referred to as a drive voltage V1, and the drive voltage of the data holding RAM 135 is referred to as a drive voltage V2. The drive voltages V1 and V2 may be generated by a generation circuit provided inside the power supply unit 150 or may be generated by a generation circuit provided separately from the power supply unit 150.

  In addition, the work RAM 134 and the data holding RAM 135 receive supply of reference voltages Vr1 and Vr2 used for data determination from the power supply unit 150, respectively. The reference voltages Vr1 and Vr2 may be generated by a reference voltage generation circuit 151 provided separately from the power supply unit 150, or may be generated by a generation circuit provided inside the power supply unit 150.

  Here, the work RAM 134 serves as a work area (main memory) for developing and executing program data stored in the ROM 131. For this reason, in the normal state, the power supply unit 150 supplies power to the work RAM 134.

  When shifting from the normal state to the power saving state, the power supply unit 150 stops supplying power to the work RAM 134. For example, in order to cut off the power supply from the power supply unit 150 to the work RAM 134, the main control unit 110 switches the switch unit 152 connecting the work RAM 134 and the power supply unit 150 from on to off.

  At this time, if the activation image (program data expanded in the work RAM 134) is stored as it is in the work RAM 134, the activation image is lost. Therefore, when returning from the power saving state to the normal state, it is necessary to start from the process of reading the program data written in the ROM 131 again, so that it takes time until the apparatus is started.

  As a method for solving this inconvenience, the startup image is saved from the work RAM 134 to a non-volatile memory (ROM, etc.) when shifting from the normal state to the power saving state, and is started when the normal state is restored from the power saving state. It is conceivable to return the image from the nonvolatile memory to the work RAM 134. According to this method, even if the power supply to the work RAM 134 is interrupted when shifting from the normal state to the power saving state, the startup image before entering the power saving state can be retained. For this reason, when returning from the power saving state to the normal state, the apparatus starts up quickly, which is convenient for the user. However, a non-volatile memory having a large memory capacity is required, leading to an increase in cost.

  As another method, it is also conceivable to use only a part of the work RAM 134 (for example, to self-refresh only a predetermined bank or chip) in the power saving state. According to this, the power saving effect is enhanced as compared with the case where all the parts of the work RAM 134 are used. However, if the entire part of the work RAM 134 cannot be used, the convenience for the user is reduced. In addition, a complicated circuit is required, leading to an increase in cost.

  Therefore, in this embodiment, a data holding RAM 135 is provided separately from the work RAM 134. The data holding RAM 135 has a smaller memory capacity than the work RAM 134 (the number of memory chips mounted is small). For example, the memory capacity of the data holding RAM 135 is about 1/4 to 1/16 of the memory capacity of the work RAM 134. The bus width (for example, 16 bits) of the memory bus MB connected to the data holding RAM 135 is narrower than the bus width (for example, 32 bits) of the memory bus MB connected to the work RAM 134.

  The data holding RAM 135 does not hold data in the normal state. That is, in the normal state, the main control unit 110 uses only the work RAM 134 as a work area and does not use the data holding RAM 135 as a work area. Therefore, when shifting from the normal state to the power saving state, the memory area of the data holding RAM 135 is an empty area.

  Further, the data holding RAM 135 receives power supply from the power supply unit 150 regardless of the normal state and the power saving state. That is, the power supply unit 150 supplies power to both the work RAM 134 and the data holding RAM 135 in the normal state, and stops supplying power to the work RAM 134 when the normal state is shifted to the power saving state. The power supply to the data holding RAM 135 is continued.

  When shifting from the normal state to the power saving state, the main control unit 110 compresses the data held in the work RAM 134 (the startup image before entering the power saving state) and stores the data in the data holding RAM 135. Evacuate. Thereby, even if the power supply to the work RAM 134 is cut off, the activation image before entering the power saving state is held in the data holding RAM 135. At this time, the power supply to the data holding RAM 135 is continued. However, since the memory capacity of the data holding RAM 135 is smaller than the memory capacity of the work RAM 134, the power supply to the work RAM 134 is continued (entering the power saving state). Compared with the case where the previous activation image is held in the work RAM 134 as it is, the power consumption can be suppressed.

  Thereafter, when returning from the power saving state to the normal state, the main control unit 110 decompresses the data (startup image before entering the power saving state) saved in the data holding RAM 135 to the work RAM 134. Let me receive it. That is, after returning from the power saving state to the normal state, the work RAM 134 having a large memory capacity becomes a work area, so the processing speed does not decrease. At this time, it is not necessary to start from the process of re-reading the program data written in the ROM 131, so that the apparatus can be activated quickly.

  Next, the operation of the RAM 132 when shifting from the normal state to the power saving state (when returning from the power saving state to the normal state) will be described with reference to FIG.

  First, it is assumed that program data or the like is expanded in the work RAM 134 (the activation image is held in the work RAM 134) at the start of the flow of FIG. At this time, it is assumed that both the work RAM 134 and the data holding RAM 135 are supplied with power from the power supply unit 150. Then, after the use of the device is finished, when a certain time has passed without using the device (when shifting from the normal state to the power saving state), the flow of FIG. 4 starts. Alternatively, the flow of FIG. 4 also starts when the operation panel 101 receives an instruction to shift from the normal state to the power saving state.

  In step S <b> 1, the main control unit 110 compresses the data (startup image) held in the work RAM 134 and saves it in the data holding RAM 135.

  In step S <b> 2, the main control unit 110 cuts off power supply from the power supply unit 150 to the work RAM 134. That is, the main control unit 110 switches the switch unit 152 that connects the work RAM 134 and the power supply unit 150 from on to off. However, the main control unit 110 continues to supply power from the power supply unit 150 to the data holding RAM 135.

  In step S3, the main control unit 110 determines whether or not a signal indicating that the condition for returning from the power saving state to the normal state is satisfied is received. As a result of the determination, if a signal indicating that the condition for returning from the power saving state to the normal state is received, the process proceeds to step S4, and the condition for returning from the power saving state to the normal state is satisfied. If the signal indicating is not received, the operation of step S3 is repeated.

  In step S <b> 4, the main control unit 110 resumes power supply from the power supply unit 150 to the work RAM 134. That is, the main control unit 110 switches the switch unit 152 that connects the work RAM 134 and the power supply unit 150 from OFF to ON.

  In step S <b> 5, the main control unit 110 decompresses the data saved in the data holding RAM 135 and moves it to the work RAM 134.

  In the present embodiment, as described above, when the power supply unit 150 shifts from the normal state to the power saving state, the power holding unit 135 stops the supply of power to the work RAM 134 (first volatile memory) and the data holding RAM 135 ( Electric power is supplied to the second volatile memory. Therefore, when entering the power saving state from the normal state, the data stored volatilely in the work RAM 134 before entering the power saving state is saved in the data holding RAM 135 before entering the power saving state. The data stored in the work RAM 134 in a volatile manner is not lost (stored in the data holding RAM 135). Therefore, when returning from the power saving state to the normal state, it is not necessary to read out data from the ROM 131 again and expand it, and the apparatus can be quickly started up.

  Further, since the data holding RAM 135 that supplies power in the power saving state has a smaller memory capacity than the work RAM 134, power is supplied to the work RAM 134 in the power saving state (before entering the power saving state). Compared with the case where the data stored in the work RAM 134 is stored volatilely, the power consumption is reduced and the power saving effect is enhanced.

  Further, since the data holding RAM 135 for saving data is inexpensive, an increase in cost can be suppressed.

  In the present embodiment, as described above, the data holding RAM 135 does not hold data in the normal state. With this configuration, the memory area of the data holding RAM 135 is an empty area when shifting from the normal state to the power saving state. Therefore, when shifting from the normal state to the power saving state, it is possible to easily secure a memory area for saving data.

  In the present embodiment, as described above, the work RAM 134 receives data saved in the data holding RAM 135 from the data holding RAM 135 when the work RAM 134 returns from the power saving state to the normal state. According to this configuration, after returning from the power saving state to the normal state, the work RAM 134 having a larger memory capacity than the data holding RAM 135 becomes a work area, so that the processing speed does not decrease.

  In the present embodiment, as described above, the main control unit 110 (processing unit) performs compression processing on data to be saved from the work RAM 134 to the data holding RAM 135. With this configuration, the memory capacity of the data holding RAM 135 is smaller than the memory capacity of the work RAM 134, so that there is a disadvantage that data cannot be saved (the memory capacity is insufficient). Can be suppressed.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is shown not by the description of the above-described embodiment but by the scope of claims for patent, and further includes meanings equivalent to the scope of claims for patent and all modifications within the scope.

100 Image forming apparatus 110 Main control unit (processing unit)
134 Work RAM (first volatile memory)
135 Data retention RAM (second volatile memory)
150 Power supply

Claims (4)

A first volatile memory serving as a work area for decompressing and executing the data;
A second volatile memory having a smaller memory capacity than the first volatile memory;
A power supply unit for supplying power to the first volatile memory and the second volatile memory,
The power supply unit supplies power to the second volatile memory while stopping the supply of power to the first volatile memory when transitioning from a normal state to a power saving state,
The first volatile memory saves data stored before entering the power saving state to the second volatile memory when shifting from the normal state to the power saving state. .   The image forming apparatus according to claim 1, wherein the second volatile memory does not hold data in a normal state.   The first volatile memory receives data saved in the second volatile memory from the second volatile memory when returning from a power saving state to a normal state. The image forming apparatus described in 1.   The image forming apparatus according to claim 1, further comprising a processing unit that performs compression processing on data to be saved from the first volatile memory to the second volatile memory.

Images