Abstract:
An information processing device includes an execution unit that executes a control program for causing a functional unit to realize a predetermined function, a memory that stores the control program, a state variable indicating a state of the functional unit, and activation history of either initial activation or second and following activation, in a nonvolatile memory, and a communication unit that causes the execution unit to communicate with the functional unit, wherein the execution unit includes a first procedure where the control program is stored in the memory and the control program is read and is executed, and a second procedure where the control program pre-stored in the memory is read and is executed, refers to the activation history when activation is performed, executes the first procedure in a case of the initial activation, and executes the second procedure in a case of the second and following activation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2012-049643 filed Mar. 6, 2012. 
     BACKGROUND 
     Technical Field 
     The present invention relates to an information processing device, an image forming apparatus, and a non-transitory computer readable medium. 
     SUMMARY 
     According to an aspect of the invention, there is provided an information processing device including an execution unit that executes a control program for causing a functional unit connected to an external device to realize a predetermined function, a memory that stores the control program, a state variable indicating a state of the functional unit, and activation history of either initial activation or second and following activation, in a nonvolatile memory which is readable and writable and maintains information stored therein even if power is not supplied, and a communication unit that causes the execution unit to communicate with the functional unit, wherein the execution unit includes a first procedure where the control program is stored in the memory and the control program is read and is executed, and a second procedure where the control program pre-stored in the memory is read and is executed without storing the control program in the memory, refers to the activation history when activation is performed, executes the first procedure in a case of the initial activation, executes the second procedure in a case of the second and following activation, and acquires a state variable indicating a state of the functional unit through communication with the functional unit with the communication unit and stores the state variable in the memory, so as to be transferred to an operable state. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a diagram illustrating an example of the configuration of an image forming system according to an exemplary embodiment. 
         FIG. 2  is a hardware block diagram illustrating an example of the internal configuration of a controller provided in an image forming apparatus. 
         FIG. 3  is a diagram illustrating an example of the configuration of a memory map formed by a main memory. 
         FIG. 4  is a flowchart illustrating an activation process of the image forming apparatus. 
         FIG. 5  is a sequence diagram illustrating an example of the communication control between the controller and each constituent element in the first activation process. 
         FIG. 6  is a flowchart illustrating second and following activation processes of the image forming apparatus. 
         FIG. 7  is a sequence diagram illustrating an example of the communication control between the controller and each constituent element in the second and following activation processes. 
         FIGS. 8A and 8B  are diagrams illustrating the time required for the first activation process and the second and following activation processes through comparison. 
         FIG. 9  is a diagram illustrating overwriting of programs and variables in a program/variable development region. 
         FIG. 10  is a sequence diagram illustrating an example of the communication control between the controller and the respective constituent elements in an activation process when an affirmative response signal is not received from any of the respective constituent elements. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a diagram illustrating an example of the configuration of an image forming system according to an exemplary embodiment. 
     This image forming system includes an image forming apparatus  1  which is operated as a so-called multi-function peripheral having a scanning function, a printing function, a copying function, and a facsimile function, a network  2  connected to the image forming apparatus  1 , a terminal apparatus  3  connected to the network  2 , a facsimile apparatus  4  connected to the network  2 , and a server apparatus  5  connected to the network  2 . 
     Here, the network  2  includes an internet line or a telephone line. In addition, the terminal apparatus  3  instructs the image forming apparatus  1  to form images via the network  2 , and includes, for example, a PC (Personal Computer). In addition, the facsimile apparatus  4  transmits and receives facsimiles to and from the image forming apparatus  1  via the network  2 . Further, the server apparatus  5  transmits and receives data (including programs) to and from the image forming apparatus  1  via the network  2 . 
     In addition, the image forming apparatus  1  includes an image reading unit  10  which reads images recorded on a recording material such as paper, an image forming unit  20  which forms images on a recording material such as paper, a user interface (UI)  30  which receives instructions related to operations using the scanning function, the printing function, the copying function, and the facsimile function from a user and displays messages to the user, a transmission and reception unit  40  which transmits and receives data to and from the terminal apparatus  3 , the facsimile apparatus  4  and the server apparatus  5  via the network  2 , and a controller  50  which controls operations of the image reading unit  10 , the image forming unit  20 , the UI  30 , and the transmission and reception unit  40 . Further, in the image forming apparatus  1 , the scanning function is realized by the image reading unit  10 , the printing function is realized by the image forming unit  20 , the copying function is realized by the image reading unit  10  and the image forming unit  20 , and the facsimile function is realized by the image reading unit  10 , the image forming unit  20 , and the transmission and reception unit  40 . In addition, the transmission and reception unit  40  may be provided as one for the Internet line and one for a telephone line separately. 
     The image reading unit  10 , the image forming unit  20 , the UI  30 , the transmission and reception unit  40 , and the like are an example of the functional units. 
       FIG. 2  is a hardware block diagram illustrating an example of the internal configuration of the controller  50  provided in the image forming apparatus  1  shown in  FIG. 1 . 
     The controller  50  as an example of the information processing device includes a CPU (Central Processing Unit)  51  as an example of the execution unit which controls the respective units of the image forming apparatus  1  by executing various operations, and a bus bridge  52  which is connected to the CPU  51  and transmits and receives a variety of data to and from the CPU  51 . In the controller  50 , the bus bridge  52  is connected to a memory bus  53  which performs transmission and reception of data at a first clock and a PCI (Peripheral Component Interconnect) bus  54  which performs transmission and reception of data at a second clock of lower frequency than the first clock. 
     In addition, the controller  50  includes a ROM (Read Only Memory)  55 , a nonvolatile RAM (Random Access Memory)  56 , and a volatile RAM  57 . The ROM  55 , the nonvolatile RAM  56 , and the volatile RAM  57  are connected to the memory bus  53 . 
     Further, the controller  50  includes a UI interface circuit (UI IF)  61  for controlling the UI  30 , a scan interface circuit (scan IF)  62  for controlling the image reading unit  10 , a print interface circuit (print IF)  63  for controlling the image forming unit  20 , a network interface circuit (network IF)  64  for controlling the transmission and reception unit  40 , and a general purpose interface circuit (general purpose IF)  65  for controlling a general purpose interface such as a USB (Universal Serial Bus). In addition, the UI IF 61 , the scan IF  62 , the print IF  63 , the network IF  64 , and the general purpose IF  65  are connected to the PCI bus  54 . In addition, in the exemplary embodiment, a card reader  70  which reads and writes data from and into, for example, an installed memory card is connected to the general purpose IF  65 . 
     The UI IF 61 , the scan IF  62 , the print IF  63 , the network IF  64 , the general purpose IF  65 , and the PCI bus  54  are an example of the communication unit. 
     In addition, the controller  50  further includes a clock generator  58  which generates a reference clock which is used as a clock reference where the respective units (the CPU  51  and the like) constituting the controller  50  operate, and a timer  59  which performs clocking according to an operation of the CPU  51  and the like. 
     The controller  50  is powered on and off by a main switch MSw. In addition, the UI  30 , the image reading unit  10 , the image forming unit  20 , the transmission and reception unit  40 , and the card reader  70  are powered on and off by sub-switches SSw 1  to SSw 5  which are controlled by the controller  50 . 
     The controller  50  in the exemplary embodiment is constituted by, for example, a one-chip microcontroller. However, the controller  50  may be constituted by plural chips. 
     In addition, in the controller  50  of the exemplary embodiment, the CPU  51  can directly access the ROM  55 , the nonvolatile RAM  56 , and the volatile RAM  57 . In the following description, the ROM  55 , the nonvolatile RAM  56 , and the volatile RAM  57  connected to the memory bus  53  are collectively referred to as a “main memory” in some cases. 
     Here, the ROM  55  as a storage device includes a so-called mask ROM, a variety of PROMs (Programmable ROMs: for example, an OTP ROM (One Time Programmable ROM), a UV-EPROM (Ultra-Violet Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM)), a flash memory, and the like. In addition, in this example, the flash memory is used as the ROM  55 . 
     In addition, the nonvolatile RAM  56  as an example of the storage device includes a nonvolatile memory which can maintain information even if power is not supplied thereto, such as an MRAM (Magnetoresistive RAM), a FeRAM (Ferroelectric RAM), a PRAM (Phase change RAM), a ReRAM (Resistance RAM). In addition, in this example, the MRAM which can read and write data at higher speed than the flash memory used as the ROM  55 , is used as the nonvolatile RAM  56 . 
     In addition, the volatile RAM  57  includes a volatile memory which may not maintain information unless power is supplied, such as a DRAM (Dynamic RAM) or an SRAM (Static RAM). Further, in this example, the DRAM is used as the volatile RAM  57 . 
     In the exemplary embodiment, the nonvolatile RAM  56  and the volatile RAM  57  read and write data together at the first clock. For this reason, the nonvolatile RAM  56  has a reading and writing performance equivalent to that of the volatile RAM  57  (in this example, DRAM). 
     When the main switch MSw is turned off, storage contents of register groups and cache memories (also constituted by a volatile memory) provided in the CPU  51  are cleared. In addition, storage contents of the volatile RAM  57  provided in the controller  50  are also cleared. On the other hand, even if the main switch MSw is turned off, storage contents of the ROM  55  and the nonvolatile RAM  56  provided in the controller  50  are not cleared. Further, the nonvolatile RAM  56  maintains contents stored before the main switch MSw is turned off. 
     Further, when an initial program loader (IPL) described later is also activated, storage contents of the register groups and the cache memories provided in the CPU  51  are cleared (reset). 
       FIG. 3  is a diagram illustrating an example of the configuration of a memory map formed by the above-described main memory (the ROM  55 , the nonvolatile RAM  56 , and the volatile RAM  57 ). 
     In this example, a compressed OS region A 01  and a compressed program region A 02  are disposed in the ROM  55 . An OS development region A 11 , a program/variable development region A 12 , and a history region A 13  are disposed in the nonvolatile RAM  56 . In addition, the history region A 13  includes an activation flag region A 13   a  which stores an activation flag as an example of the activation history, a constituent element status region A 13   b  which stores a constituent element status, and a log region A 13   c  which stores a log. In addition, a work region A 21  and a buffer region A 22  are disposed in the volatile RAM  57 . 
     Among them, the compressed OS region A 01  disposed in the ROM  55  stores an initial program loader (IPL) and an operation system (OS) (compressed OS) as an example of the compressed basic program, which are programs executed by the CPU  51  in the controller  50 , when the image forming apparatus  1  is activated. In addition, the compressed program region A 02  disposed in the ROM  55  stores a program as an example of the control program for operating each constituent element capable of being mounted in the image forming apparatus  1  of the exemplary embodiment, and variables as an example of the state variables used in the program, in a state of being collected and compressed for each constituent element. For example, in the example shown in  FIG. 3 , the compressed program region A 02  stores a compressed program (compressed program for constituent element  1 ) where a program and variables for operating a constituent element  1  are compressed, a compressed program (compressed program for constituent element  2 ) where a program and variables for operating a constituent element  2  are compressed, a compressed program (compressed program for constituent element  3 ) where a program and variables for operating a constituent element  3  are compressed, and the like. In addition, the constituent elements  1 ,  2 ,  3 , . . . , described here respectively correspond to the image reading unit  10 , the image forming unit  20 , the UI  30 , the transmission and reception unit  40 , the card reader  70 , and the like described above, which are attachable to and detachable from the main body of the image forming apparatus  1 , and perform predefined functions singly or along with other constituent elements when installed in the image forming apparatus  1 . 
     As such, in the exemplary embodiment, plural compressed programs corresponding to the respective constituent elements capable of being mounted in the image forming apparatus  1  are stored in advance in the compressed program region A 02  disposed in the ROM  55 , regardless of constituent elements (the image forming apparatus  1  shown in  FIG. 1  does not include the card reader  70 ) of the image forming apparatus  1  which are actually used. Thereby, exchange of the ROM  55  or update of the programs stored in the ROM  55  due to change in a device constituent element of the image forming apparatus  1  may not be performed. 
     Next, the OS development region A 11  disposed in the nonvolatile RAM  56  stores an OS obtained by the CPU  51  developing (decompressing) the compressed OS stored in the ROM  55 . 
     The program/variable development region A 12  stores a program and variables which are obtained by the CPU  51  developing the compressed program read from the above-described compressed program region A 02 . For example, in the example shown in  FIG. 3 , the program/variable development region A 12  stores a program and variables for operating the constituent element  1  (program/variable for constituent element  1 ), a program and variables for operating the constituent element  2  (program/variable for constituent element  2 ), a program and variables for operating the constituent element  3  (program/variable for constituent element  3 ), . . . . 
     In addition, the variables are parameters which can be rewritten so as to correspond to variations in functions of the respective constituent elements. The compressed program has an initial value of each of the variables. The variables will be described later. 
     In addition, in the history region A 13  disposed in the nonvolatile RAM  56 , the activation flag region A 13   a  stores a flag (activation flag) indicating whether or not the image forming apparatus  1  is activated in the past. Here, the activation flag region A 13   a  stores “On (1)” if the image forming apparatus  1  is activated in the past, and stores “Off (0)” if the image forming apparatus  1  is not activated in the past. In addition, in the history region A 13  disposed in the nonvolatile RAM  56 , the constituent element status region A 13   b  stores a device constituent element when the image forming apparatus is previously activated (hereinafter, referred to as a “previous device constituent element”) as a constituent element status. Here, in the constituent element status region A 13   b , in relation to each constituent element which may be installed in the image forming apparatus  1 , “On (1)” is stored if there is the constituent element, and, “Off (0)” is stored if there is no constituent element. Furthermore, in the history region A 13  disposed in the nonvolatile RAM  56 , the log region A 13   c  stores contents of instructions received by the image forming apparatus  1 , contents when a device constituent element is changed, contents of generated errors, and the like, as log data. 
     In addition, the work region A 21  disposed in the volatile RAM  57  stores data which is temporarily generated when the CPU  51  executes programs. The buffer region A 22  disposed in the volatile RAM  57  stores data regarding instructions (data output to the respective IFs (in this example, the UI IF 61 , the scan IF  62 , the print IF  63 , the network IF  64 , and the general purpose IF  65 ) via the PCI bus  54 ) output to each constituent element of the image forming apparatus  1  when the CPU  51  processes data. 
     Here, the variables are described. 
     The variables are parameters which are necessary for the controller  50  to refer to when performing functions of each constituent element and vary when each constituent element performs functions. Therefore, the variables may be referred to as parameter variables in some cases. 
     For example, if a constituent element is the image reading unit  10 , the variables are parameters regarding a CCD for performing image reading. Characteristics of the CCD vary with the passage of time or temperature. Therefore, parameters for correcting disparities due to temperature, heat, voltage, and the like of the CCD are necessary as variables. In addition, the variables vary according to variations in states of the image reading unit  10 . 
     If a constituent element is the image forming unit  20 , an amount of paper or the like, an amount of toner, and the like are necessary as variables. 
     In addition, if a constituent element is the transmission and reception unit  40 , a calendar, the time of day, a period (timer), and the like are necessary as variables. 
     As described above, the variables are parameters corresponding to constituent element states, and thus are necessary to read and rewrite from a connected constituent element, for example, even when the image forming apparatus  1  is powered on (main switch MSw described later) and is activated. In addition, in a case where a constituent element is operated and thereby variables vary, the variables are necessary to rewrite for each case of the variation. 
     For example, if a constituent element is the image forming unit  20 , when a cassette holding paper or the like is drawn and inserted, an amount of paper or the like may be increased or decreased. Therefore, the image forming unit  20  acquires variables regarding an amount of paper or the like using the drawing and inserting of the cassette as a trigger and transmits the acquired variables to the controller  50 . 
     In other words, the constituent elements such as the image reading unit  10 , the image forming unit  20 , and the transmission and reception unit  40  detect variations in the respective states and transmit variables to the controller  50 . In addition, in the controller  50 , the CPU  51  rewrites variables of the program/variable development region A 12  corresponding to each constituent element. 
     The variables are referred to by the CPU  51  in the controller  50  and are used to control the respective constituent elements such as the image reading unit  10 , the image forming unit  20 , and the transmission and reception unit  40 . In addition, some of the variables are transmitted to the UI  30  and are used for display of states of the constituent elements such as the image reading unit  10 , the image forming unit  20 , and the transmission and reception unit  40 , and issuing of alerts for paper supply request or the like to the user. 
     Next, an activation process of the image forming apparatus  1  will be described. 
       FIG. 4  is a flowchart illustrating an activation process of the image forming apparatus  1  shown in  FIG. 1 .  FIG. 4  shows an operation of the CPU  51 . Here, the image forming apparatus  1  includes a constituent element  1 , a constituent element  2 , a constituent element  3 , . . . . In addition, the constituent element  1 , the constituent element  2 , the constituent element  3 , . . . are connected to the image forming apparatus  1  via the respective IFs (in the example shown in  FIG. 2 , the UI IF 61 , the scan IF  62 , the print IF  63 , the network IF  64 , and the general purpose IF  65 ) provided in the controller  50  of the image forming apparatus  1 . In addition, the controller  50  of the image forming apparatus  1  enters ON and OFF states by the main switch MSw, and the constituent element  1 , the constituent element  2 , the constituent element  3 , . . . enter ON and OFF states by sub-switches SSw 1 , SSw 2 , SSw 3 , . . . . 
     When the main switch MSw of the controller  50  is turned on (step S 1 ), the CPU  51  reads the initial program loader (IPL) stored in the OS region A 01  of the ROM  55  via the bus bridge  52  and the memory bus  53  and activates the read IPL (step S 2 ). 
     When the IPL is executed, the CPU  51  first detects device constituent elements of the image forming apparatus  1  using the respective IFs connected via the bus bridge  52  and the PCI bus  54  (step S 3 ). Here, it is assumed that the constituent element  1 , the constituent element  2 , the constituent element  3 , . . . included in the image forming apparatus  1  are detected. 
     In addition, in step S 3 , for example, a hardware method of detecting whether or not a connector or the like is physically connected to each IF may be used, and, for example, a software method of detecting whether or not communication can be performed with a connection target via each IF may be used. 
     Next, an activation flag is read and acquired from the activation flag region A 13   a  in the history region A 13  of the nonvolatile RAM  56  (step S 4 ). In addition, the CPU  51  determines whether or not the activation flag is Off (0), that is, whether or not the present activation is an initial activation (step S 5 ). Hereinafter, a case where affirmative determination (Yes) is performed in step S 4  will be described, and a case (a case of A in  FIG. 4 ) where negative determination (No) is performed will be described later (refer to  FIG. 6  described later). 
     In a case where affirmative determination (Yes) is performed in step S 5 , that is, the present activation process is an initial activation process, the CPU  51  reads a compressed OS from the compressed OS region A 01  of the ROM  55  so as to be developed, and stores the developed OS in the OS development region A 11  in the nonvolatile RAM  56  (step S 6 ). In addition, the developed OS (hereinafter, referred to as an OS) is activated from the OS development region A 11  in the nonvolatile RAM  56  (step S 7 ). From here, the CPU  51  is changed to the IPL and is controlled by the OS. Here, steps S 6  and S 7  are an example of the third procedure. 
     Next, the CPU  51  turns on a sub-switch SSwX (where X is 1, 2, 3, . . . ) corresponding to a single constituent element included in the device constituent elements via the controller  50  (step S 8 ). It is determined whether or not the sub-switches SSw 1 , SSw 2 , SSw 3 , . . . of all the constituent elements are turned on in the present device constituent elements detected in step S 3  (step S 9 ). If negative determination (No) is performed in step S 9 , the flow returns to step S 8  where the sub-switches SSwX of the remaining constituent elements of the present device constituent elements are continued to be turned on. As described above, the sub-switches SSw 1 , SSw 2 , SSw 3 , . . . are controlled by the controller  50 . 
     When the sub-switches SSw 1 , SSw 2 , SSw 3 , . . . are turned on, the constituent element  1 , the constituent element  2 , the constituent element  3 , . . . respectively perform initialization (refer to  FIG. 5  described later). Each constituent element includes a processor or a ROM for controlling the constituent element by executing various operations in the same manner as the CPU  51 . In addition, when the initialization is performed, stored contents of a register group and a cache memory (also constituted by a volatile memory) provided in the processor are cleared, and then a program for controlling each constituent element is read from the ROM and is set in the register group. Thereby, transition to an operable state is performed. 
     In addition, the constituent element  1 , the constituent element  2 , the constituent element  3 , . . . also perform the initialization when receiving a reset signal Rst as an example of the initialization signal from the CPU  51 . 
     Next, the CPU  51  reads (transmits) a compressed program corresponding to a single constituent element included in the device constituent elements from the compressed program region A 02  of the ROM  55 , develops the compressed program read, and stores a program and variables obtained by developing the compressed program in the program/variable development region A 12  of the nonvolatile RAM  56  (step S 10 ). Thereafter, the CPU  51  activates the program (step S 11 ) and transmits a response request signal Req (denoted by a Req signal in  FIG. 4 ) for establishing communication (synchronizing) with the corresponding constituent element (step S 12 ). Steps S 10  and S 11  are an example of the first procedure. 
     In relation to the present device constituent elements detected in step S 3 , it is determined whether or not storage of programs and variables corresponding to all the constituent elements in the program/variable development region A 12 , activation of the programs, and transmission of the response request signal Req are completed (step S 13 ). If negative determination (No) is performed in step S 13 , the flow returns to step S 10 , compressed programs corresponding to the remaining constituent elements of the present device constituent elements are read, and development of the compressed programs read, storage of programs and variables obtained through the development, activation of the programs, and transmission of the response request signal Req are continued to be performed. 
     Then, when finishing a process (response process) for the response request signal Req, the constituent element  1 , the constituent element  2 , the constituent element  3 , . . . transmit an affirmative response signal Ack to the CPU  51  via the respective IFs. 
     Therefore, the CPU  51  determines whether or not the affirmative response signal Ack is received (step S 14 ). If affirmative determination (Yes) is performed in step S 14 , the CPU  51  requests the constituent elements from which the affirmative response signal Ack is received in step S 14  to transmit variables and receives the variables. In addition, the CPU  51  stores (rewrites) the variables in regions corresponding to the constituent elements of the program/variable development region A 12  of the nonvolatile RAM  56  with the received variables (step S 15 ). 
     In relation to the present device constituent elements detected in step S 3 , it is determined whether or not reception of the affirmative response signal Ack corresponding to all the constituent elements, and reception and storage of variables are completed (step S 16 ). If negative determination (No) is performed in step S 16 , the flow returns to step S 14 , and reception of the affirmative response signal Ack corresponding to the remaining constituent elements of the present device constituent elements, and reception and storage of variables are continued to be performed. 
     In addition, if the affirmative response signal Ack is not received in step S 14  (negative determination (No) is performed in step S 14 ), the CPU  51  transmits generation of errors (error information) to the UI  30  (step S 20 ), stopping (halt) (denoted by HLT in  FIG. 4 ) may be performed, or, as described later, the reset signal Rst may be transmitted to a constituent element from which the affirmative response signal Ack is not received so as to perform initialization again. In a case where the initialization is performed again, the response request signal Req is transmitted again, and it is determined whether or not the affirmative response signal Ack may be received (refer to  FIGS. 6 and 9  described later). 
     The CPU  51  stores “On (1)” in the activation flag region A 13   a  in the history region A 13  of the nonvolatile RAM  56  as an activation flag (step S 17 ). Next, the CPU  51  stores a constituent element status that constituent elements which exist are in an “On (1)” state and constituent elements which do not exist are in an “Off (0)” state, in the constituent element status region A 13   b  in the history region A 13  (step S 18 ). In addition, a log on which the device constituent elements and contents of executed processes are reflected is created, and the created log is stored in the log region A 13   c  of the history region A 13  (step S 19 ). 
     In this way, the activation process of the image forming apparatus  1  finishes, and the image forming apparatus  1  enters an operable state (standby state). 
     When the use of the image forming apparatus  1  finishes, the sub-switches SSw 1 , SSw 2 , SSw 3 , . . . and the main switch MSw are turned off. This is performed through a series of operations where a user gives an instruction for turning off the switches to the UI  30 , thus the CPU  51  turns off the sub-switches SSw 1 , SSw 2 , SSw 3 , . . . and then turns off the main switch MSw. 
     In addition, when the image forming apparatus  1  is not used, in order to reduce power (energy) consumption (save energy), the CPU  51  may perform determination according to predefined conditions, and turn off the sub-switches SSw 1 , SSw 2 , SSw 3 , . . . and the main switch MSw. 
       FIG. 5  is a sequence diagram illustrating an example of the communication control between the controller  50  and the respective constituent elements (constituent elements  1 ,  2 ,  3 ,) in the initial activation process. In  FIG. 5 , the time proceeds from the above to the below on the figure. In  FIG. 5 , the same steps as shown in  FIG. 4  are given the same reference numerals. In addition, in a case where the constituent elements  1 ,  2 ,  3 , . . . respectively are indicated so as to be divided, the numbers of the constituent elements  1 ,  2 ,  3 , . . . are added following the hyphen (-). 
     As described above, the controller  50 , that is, the CPU  51  (denoted by the controller  50  in  FIG. 5 , and, hereinafter, denoted by the controller  50  (CPU  51 )) performs communication with the constituent elements  1 ,  2 ,  3 , . . . via the respective IFs so as to acquire variables from the constituent elements  1 ,  2 ,  3 , . . . provided in the image forming apparatus  1 . 
     The controller  50 , that is, the CPU  51  reads and develops a compressed OS, stores the developed OS (step S 6 ), and activates the OS (step S 7 ). In addition, the controller  50  (CPU  51 ) turns on the sub-switches SSw 1 , SSw 2 , SSw 3 , . . . (steps S 8 - 1 , S 8 - 2 , S 8 - 3 , . . . ). Thereby, each of the constituent elements  1 ,  2 ,  3 , . . . performs initialization (steps S 101 - 1 , S 101 - 2 ,  101 - 3 , . . . ). The initialization is performed independently for each of the constituent elements  1 ,  2 ,  3 , . . . . 
     In addition, the controller  50  (CPU  51 ) reads and develops the compressed program for constituent element  1 , the compressed program for constituent element  2 , the compressed program for constituent element  3 , . . . corresponding to the constituent elements  1 ,  2 ,  3 , . . . , stores the developed program/variable for constituent element  1 , program/variable for constituent element  2 , program/variable for constituent element  3 , . . . , and activates the program for constituent element  1 , the program for constituent element  2 , the program for constituent element  3 , . . . (steps S 10 - 1 , S 10 - 2 , S 10 - 3 , . . . , and steps S 11 - 1 , S 11 - 2 , S 11 - 3 , . . . ). Further, response request signals Req 1 ,  2 ,  3 , . . . are respectively transmitted to the constituent elements  1 ,  2 ,  3 , . . . (steps S 12 - 1 , S 12 - 2 , S 12 - 3 , . . . ). 
     When receiving the corresponding response request signal Req 1 ,  2 ,  3 , . . . , the constituent elements  1 ,  2 ,  3 , . . . perform a process (response process) for response to the controller  50  (CPU  51 ) (steps S 102 - 1 , S 102 - 2 , S 102 - 3 , . . . ). In addition, the constituent elements  1 ,  2 ,  3 , . . . transmit affirmative response signals Ack 1 ,  2 ,  3 , . . . to the controller  50  (CPU  51 ). 
     The controller  50  (CPU  51 ) receives the affirmative response signals Ack 1 ,  2 ,  3 , . . . from the constituent elements  1 ,  2 ,  3 , . . . (steps S 14 - 1 , S 14 - 2 , S 14 - 3 , . . . ). Thereby, communication is established between the controller  50  (CPU  51 ) and each of the constituent elements  1 ,  2 ,  3 , . . . . Thereafter, the controller  50  (CPU  51 ) acquires variables from each of the constituent elements  1 ,  2 ,  3 , . . . , and rewrites variables by storing the variables in corresponding regions (refer to  FIG. 3 ) of the program/variable development region A 12  of the nonvolatile RAM  56  (steps S 15 - 1 , S 15 - 2 , S 15 - 3 , . . . ). 
     Thereby, the image forming apparatus  1  enters an operable state (standby state). 
     In  FIG. 5 , the controller  50  (CPU  51 ) reads and develops the next compressed program and stores the developed program and variables without waiting for reception of the affirmative response signals Ack after transmitting the response request signals Req (for example, the compressed program for constituent element  2  is read and developed in step S 10 - 2  after the response request signal Req 1  is transmitted in step S 12 - 1  of  FIG. 5 ). This is because the CPU  51  has a (multitasking) function of capable of executing plural programs in parallel. 
     When the CPU  51  receives the affirmative response signals Ack while reading and developing the compressed programs and storing the developed programs and variables, the CPU requests for transmission of variables in response thereto. 
     In addition, the CPU  51  may receive the affirmative response signals Ack after transmitting the response request signals Req, and then may read and develop the next compressed program and store the developed program and variables (single task). 
     Next, a case where negative determination (No) is performed in step S 4  (the case of A in  FIG. 4 ) will be described. The case where negative determination (No) is performed in step  4  is a case of second and following activation processes. 
       FIG. 6  is a flowchart illustrating the second and following activation processes of the image forming apparatus  1 . 
     Since the acquired activation flag is On (1), the present activation corresponds to the second and following activation. Therefore, an OS and program and variables corresponding to each constituent element are stored in the program/variable development region A 12 . 
     Therefore, the CPU  51  activates a developed OS which is stored in the OS development region A 11  of the nonvolatile RAM (step S 31 ). In addition, the CPU reads (acquires) a constituent element status from the constituent element status region A 13   b  of the history region A 13  of the nonvolatile RAM  56  (step S 32 ). 
     Further, it is determined whether or not there is a change as compared with the device constituent elements detected in step S 3  shown in  FIG. 3  (step S 33 ). 
     Here, if negative determination (No) is performed, a sub-switch SSwX (where X is 1, 2, 3, . . . ) corresponding to a single constituent element included in the device constituent elements is turned on (step S 34 ). It is determined whether or not the sub-switches SSw 1 , SSw 2 , SSw 3 , . . . of all the constituent elements are turned on in the present device constituent elements detected in step S 3  shown in  FIG. 3  (step S 35 ). If negative determination (No) is performed in step S 35 , the flow returns to step S 34  where the sub-switches SSwX of the remaining constituent elements of the present device constituent elements are continued to be turned on. 
     In addition, the CPU  51  activates a program corresponding to each constituent element, which is developed and stored in the program/variable development region A 12  of the nonvolatile RAM  56  (step S 36 ). Next, the CPU  51  transmits the response request signal Req to each constituent element (step S 37 ). Step S 36  is an example of the second procedure. 
     In relation to the present device constituent elements detected in step S 3  shown in  FIG. 3 , it is determined whether or not activation of corresponding programs and variables and transmission of the response request signal Req are completed (step S 38 ). If negative determination (No) is performed in step S 38 , the flow returns to step S 36 , activation of programs corresponding to the remaining constituent elements of the present device constituent elements and transmission of the response request signal Req are continued to be performed. 
     Then, when executing and finishing a process (response process) for the response request signal Req, each constituent element transmits the affirmative response signal Ack to the CPU  51  via the respective IFs. 
     Therefore, the CPU  51  determines whether or not the affirmative response signal Ack is received (step S 39 ). Hereinafter, a case where affirmative determination (Yes) is performed in step S 39  will be described. 
     In addition, a case where negative determination (No) is performed in step S 39  will be described later. 
     If affirmative determination (Yes) is performed in step S 39 , the CPU  51  requests the constituent elements from which the affirmative response signal Ack is received in step S 39  to transmit variables and receives the variables. In addition, the CPU  51  stores (rewrites) the variables in regions corresponding to the constituent elements of the program/variable development region A 12  of the nonvolatile RAM  56  with the received variables (step S 40 ). 
     In relation to the present device constituent elements detected in step S 3  shown in  FIG. 3 , it is determined whether or not reception of the affirmative response signal Ack corresponding to all the constituent elements, and reception and storage of variables are completed (step S 41 ). If negative determination (No) is performed in step S 41 , the flow returns to step S 39 , and reception of the affirmative response signal Ack corresponding to the remaining constituent elements of the present device constituent elements, and reception and storage of variables are continued to be performed. 
     Then, the flow returns to B of the flowchart shown in  FIG. 4 , a log on which contents of the executed processes are reflected is created, and the created log is stored in the log region A 13   c  of the history region A 13  (step S 19  of  FIG. 4 ). 
     If negative determination (No) is performed in step S 33 , that is, the previous device constituent elements are different from the present device constituent elements, for example, the CPU  51  stores “Off (0)” in the activation flag region A 13   a  of the history region A 13  of the nonvolatile RAM  56  as an activation flag (reset of the activation flag) (step S 42 ). In addition, the flow may return to C of  FIG. 4 , and the IPL may be activated in step S 2 . In this case, the above-described initial activation process is performed. 
     In addition, based on the present constituent elements, programs and variables which are not stored in the program/variable development region A 12  of the nonvolatile RAM  56  may be read and developed from the ROM  55 , the developed programs and variables may be stored, the programs may be activated, and then the flow may proceed to step S 34 . At this time, the flow may not proceed to B of  FIG. 3  but returns to step S 18  of  FIG. 3  such that constituent element statuses corresponding to the present constituent elements are stored in the constituent element status region A 13   b  of the history region A 13  of the nonvolatile RAM  56 . 
       FIG. 7  is a sequence diagram illustrating an example of the communication control between the controller  50  and the respective constituent elements (constituent elements  1 ,  2 ,  3 ,) in the second and following activation processes. In  FIG. 7 , the same steps as shown in  FIG. 6  are given the same reference numerals. In addition, in a case where the constituent elements  1 ,  2 ,  3 , . . . respectively are indicated so as to be divided, the numbers of the constituent elements  1 ,  2 ,  3 , . . . are added following the hyphen (-). 
     The controller  50  (CPU  51 ) activates an OS (step S 31 ), and the controller  50  (CPU  51 ) turns on the sub-switches SSw 1 , SSw 2 , SSw 3 , . . . (steps S 34 - 1 , S 34 - 2 , S 34 - 3 , . . . ). Thereby, each of the constituent elements  1 ,  2 ,  3 , . . . performs initialization (steps S 101 - 1 , S 101 - 2 , S 101 - 3 , . . . ). The initialization is performed independently for each of the constituent elements  1 ,  2 ,  3 , . . . . 
     In addition, the controller  50  (CPU  51 ) activates the program for constituent element  1 , the program for constituent element  2 , the program for constituent element  3 , . . . corresponding to the constituent elements  1 ,  2 ,  3 , . . . (steps S 36 - 1 , S 36 - 2 , S 36 - 3 ). Further, response request signals Req 1 ,  2 ,  3 , . . . are respectively transmitted to the constituent elements  1 ,  2 ,  3 , . . . (steps S 37 - 1 , S 37 - 2 , S 37 - 3 , . . . ). 
     When receiving the corresponding response request signal Req 1 ,  2 ,  3 , . . . , the constituent elements  1 ,  2 ,  3 , . . . perform a process (response process) for response to the controller  50  (CPU  51 ) (steps S 102 - 1 , S 102 - 2 , S 102 - 3 , . . . ). In addition, the constituent elements  1 ,  2 ,  3 , . . . transmit affirmative response signals Ack 1 ,  2 ,  3 , . . . to the controller  50  (CPU  51 ). 
     The controller  50  (CPU  51 ) receives the affirmative response signals Ack 1 ,  2 ,  3 , . . . from the constituent elements  1 ,  2 ,  3 , . . . (steps S 39 - 1 , S 39 - 2 , S 39 - 3 , . . . ). Thereby, communication is established between the controller  50  (CPU  51 ) and each of the constituent elements  1 ,  2 ,  3 , . . . . Thereafter, when the communication is established between the controller  50  (CPU  51 ) and each of the constituent elements  1 ,  2 ,  3 , . . . , the controller  50  (CPU  51 ) acquires variables from each of the constituent elements  1 ,  2 ,  3 , . . . , and rewrites variables by storing the variables in corresponding regions (refer to  FIG. 3 ) of the program/variable development region A 12  of the nonvolatile RAM  56  (steps S 40 - 1 , S 40 - 2 , S 40 - 3 , . . . ). 
     Thereby, the image forming apparatus  1  enters an operable state (standby state). 
       FIGS. 8A and 8B  are diagrams illustrating the time required for the first activation process and the second and following activation processes through comparison.  FIG. 8A  shows the time required for the activation process for the first time (initial activation) and  FIG. 8B  shows the time required for the activation processes from the second time and thereafter (second and following activation). 
     As shown in  FIG. 8A , in the initial activation process, there is a necessity of the time for reading and development of a compressed OS, storage of the developed OS, reading and development of a compressed program, and storage of developed program and variables. In contrast, in the second and following activation, such time is not necessary, and thus the image forming apparatus  1  can be started in a short time. 
     As an example, in the initial activation, if 10 seconds for reading and development of a compressed OS, storage of the developed OS, and activation of the OS, and about 30 seconds for reading and development of a compressed program, storage of developed program and variables, and activation of the program are necessary, that is, the time required for the initial activation process is about 40 seconds. In contrast, in the second and following activation, since the OS and the program developed and stored in the nonvolatile RAM  56  are activated, starting can be performed in several seconds. 
     Since acquisition and storage of variables of each of the constituent elements  1 ,  2 ,  3 , . . . are necessary for each activation process, the time required for them is long. 
     As described above, in the exemplary embodiment, it is possible to shorten the time required for the second and following activation processes of the image forming apparatus  1 . For this reason, the start time of each constituent element is shortened by employing a fixing device using induction heating (IH) in the image forming unit  20 , and thereby the start time of the image forming apparatus  1  is shortened. 
     Next, referring to  FIG. 6  again, if negative determination (No) is performed in step S 39 , that is, a case where the affirmative response signal Ack is not received from any of the constituent elements  1 ,  2 ,  3 , . . . will be described. 
     At this time, the CPU  51  transmits the reset signal Rst to a constituent element (any of the constituent elements  1 ,  2 ,  3 , . . . ) from which the affirmative response signal Ack is not received, in order to perform an initialization process of the constituent element again (step S 51 ). The constituent element which receives the reset signal Rst performs the initialization process again. 
     In addition, the CPU  51  reads and develops a compressed program corresponding to the constituent element from the compressed program region A 02  of the ROM  55 , and overwrites the developed program and variables in a region corresponding to the constituent element of the program/variable development region A 12  of the nonvolatile RAM  56  (step S 52 ). In addition, the program is activated (step S 53 ). 
     Next, the CPU  51  transmits the response request signal Req to the constituent element again (step S 54 ). 
     Thereafter, the CPU  51  determines whether or not the affirmative response signal Ack is received (step S 55 ). If affirmative determination (Yes) is performed in step S 55 , the CPU  51  requests the constituent element to transmit variables and receives the variables. In addition, the CPU  51  stores (rewrites) the variables in a region corresponding to the constituent element of the program/variable development region A 12  of the nonvolatile RAM  56  with the received variables (step S 40 ). 
     In relation to the present device constituent elements detected in step S 3 , it is determined whether or not reception of the affirmative response signal Ack corresponding to all the constituent elements, and reception and storage of variables are completed (step S 41 ). If negative determination (No) is performed in step S 41 , the flow returns to step S 39 , and reception of the affirmative response signal Ack corresponding to the remaining constituent elements of the present device constituent elements, and reception and storage of variables are continued to be performed. 
     Then, the flow returns to B of the flowchart shown in  FIG. 4 , a log on which contents of the executed processes are reflected is created, and the created log is stored in the log region A 13   c  of the history region A 13  (step S 19  of  FIG. 4 ). 
     In addition, if negative determination (No) is performed in step S 55 , the CPU  51  transmits generation of errors (error information) to the UI  30  (step S 56 ), stopping (halt) (HLT) may be performed. 
       FIG. 9  is a diagram illustrating overwriting of programs and variables in the program/variable development region A 12 . The CPU  51 , in step S 52 , reads and develops a compressed program corresponding to the constituent element (the constituent element  2  in  FIG. 9 ) from the compressed program region A 02  of the ROM  55 , and overwrites the developed program and variables in a region corresponding to the constituent element (constituent element  2 ) of the program/variable development region A 12  of the nonvolatile RAM  56 . 
       FIG. 10  is a sequence diagram illustrating an example of the communication control between the controller  50  and the respective constituent elements (the constituent elements  1 ,  2 ,  3 , . . . ) in an activation process when the affirmative response signal Ack is not received from any of the respective constituent elements (the constituent elements  1 ,  2 ,  3 , . . . ). 
     In  FIG. 10 , a description is made from the steps (steps S 36 - 1 , S 36 - 2 , S 36 - 3 , . . . ) where the controller  50  (CPU  51 ) activates the program for constituent element  1 , the program for constituent element  2 , the program for constituent element  3 , . . . corresponding to the constituent elements  1 ,  2 ,  3 , . . . in  FIG. 7 . 
     Next, the controller  50  (CPU  51 ) transmits response request signals Req 1 ,  2 ,  3 , . . . to the respective constituent elements  1 ,  2 ,  3 , . . . (steps S 37 - 1 , S 37 - 2 , S 37 - 3 , . . . ). 
     Here, it is assumed that the constituent element  2  is not initialized in a normal state. 
     When receiving the corresponding response request signal Req 1 ,  2 ,  3 , . . . , the constituent elements  1 ,  2 ,  3 , . . . perform a process (response process) for response to the controller  50  (CPU  51 ) (steps S 102 - 1 , S 102 - 2 , S 102 - 3 , . . . ). 
     Then, when finishing the process (response process) for the response request signals Req 1 ,  3 , . . . , the constituent element  1 , the constituent element  3 , . . . transmit affirmative response signals Ack 1 ,  3 , . . . to the controller  50  (CPU  51 ). 
     The controller  50  (CPU  51 ) receives the affirmative response signals Ack 1 ,  3 , . . . from the constituent elements  1 ,  3 , . . . (steps S 38 - 1 , S 38 - 3 , . . . ). Thereby, communication is established between the controller  50  (CPU  51 ) and each of the constituent elements  1 ,  3 , . . . . 
     In addition, the controller  50  (CPU  51 ) acquires variables from each of the constituent elements  1 ,  3 , . . . , and rewrites variables by storing the variables in corresponding regions (refer to  FIG. 3 ) of the program/variable development region A 12  of the nonvolatile RAM  56  (steps S 40 - 1 , S 40 - 3 , . . . ). 
     However, since the constituent element  2  is not initialized in a normal state, even if the response request signal Req 2  is received and the response process (step S 102 - 2 ) is performed, the affirmative response signal Ack 2  may not be transmitted to the controller  50  (CPU  51 ). Therefore, the controller  50  (CPU  51 ) may not receive the affirmative response signal Ack 2  from the constituent element  2 . 
     At this time, in a case where the predefined time set by the timer  59  from the time point when the response request signal Req 2  is transmitted is measured, the controller  50  (CPU  51 ) determines that communication is not established (time-out), and transmits the reset signal Rst to the constituent element  2  (step S 51 ). When receiving the reset signal Rst, the constituent element  2  performs initialization (step S 103 ). 
     On the other hand, the controller  50  (CPU  51 ) reads and develops the compressed program for constituent element  2  from the compressed program region A 02  of the ROM  55 , and overwrites the developed program for constituent element  2  and variables in a region of the constituent element  2  of the program/variable development region A 12  (step S 52 ). In addition, the controller  50  (CPU  51 ) activates the program for constituent element  2  (step S 53 ) and transmits the response request signal Req again (step S 54 ). 
     When the constituent element  2  enters a normal state through the re-initialization, the constituent element  2  receives the response request signal Req 2 , performs a response process (step S 104 ), and transmits an affirmative response signal Ack 2  to the controller  50  (CPU  51 ). 
     In addition, when the controller  50  (CPU  51 ) may receive the affirmative response signal Ack 2  from the constituent element  2  (step S 55 ), communication between the controller  50  (CPU  51 ) and the constituent element  2  is established. When the communication between the controller  50  (CPU  51 ) and the constituent element  2  is established, the controller  50  (CPU  51 ) acquires variables from the constituent element  2 , and rewrites variables by storing the variables in a corresponding region of the program/variable development region A 12  of the nonvolatile RAM  56  (step S 40 - 2 ). 
     As described above, in the exemplary embodiment, for example, in relation to at least one of plural constituent elements, the CPU  51  measures the time after transmission of the response request signal Req using the timer  59 , and determines that abnormality is generated as time-out if the affirmative response signal Ack is not received even after the predefined time has elapsed. In addition, the CPU  51  transmits the reset signal Rst to a constituent element from which the affirmative response signal Ack is not received so as to initialize the constituent element, reads and develops a compressed program for the constituent element from the compressed program region A 02  of the ROM  55 , and overwrites the developed program and variables in a region corresponding to the constituent element of the program/variable development region A 12  of the nonvolatile RAM  56 . In addition, the CPU  51  activates the program and retransmits the response request signal Req. 
     As in the above-described example, if there is a problem in initialization of a constituent element, the constituent element may return to a normal state through re-initialization. In this case, the constituent element transmits the affirmative response signal Ack in response to the response request signal Req, and thereby communication is established. The activation process finishes, and the image forming apparatus  1  enters an operable state (standby state). 
     In addition, even if inconvenience is caused due to rewriting of data of a program stored in the program/variable development region A 12  of the nonvolatile RAM  56 , a compressed program is read and developed again, and the program is overwritten, thereby returning to a normal state. 
     In addition, these processes are performed under the control of the CPU  51 . 
     Further, although, in the exemplary embodiment, the compressed program region A 02  storing each compressed program is disposed in the ROM  55 , the present invention is not limited thereto. In other words, the compressed program region A 02  may be disposed in the server apparatus  5  (refer to  FIG. 1 ) connected to the image forming apparatus  1  via the network  2 , or a memory card installed in the card reader  70 . In addition, in this case, the server apparatus  5  or the memory card installed in the card reader  70  may be set as a target where each compressed program is read when the IPL is executed. 
     In addition, although, in the exemplary embodiment, the program/variable development region A 12  and the history region A 13  are disposed in the nonvolatile RAM  56 , and the work region A 21  and the buffer region A 22  are disposed in the volatile RAM  57 , the present invention is not limited thereto, and, for example, the program/variable development region A 12 , the history region A 13 , the work region A 21 , and the buffer region A 22  may be disposed in the nonvolatile RAM  56 . Further, although the compressed OS region A 01  and the compressed program region A 02  are disposed in the ROM  55 , for example, the compressed OS region A 01 , the compressed program region A 02 , the program/variable development region A 12 , the history region A 13 , the work region A 21 , and the buffer region A 22  may be disposed in the nonvolatile RAM  56 . 
     In addition, although, in the exemplary embodiment, a case where the controller  50  is incorporated into the image forming apparatus  1  has been described as an example, the present invention is not limited thereto and may be applied to an apparatus which is constituted by combinations of plural units and of which a configuration may be modified due to attachment and detachment of the plural units. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.