Abstract:
An electric device is capable of operating in a normal operation mode and a power save operation mode. The electric device includes a first processor for processing information input externally in the normal operation mode, and a second processor for processing an internal operation of the electric device in the normal operation mode. The second processor consumes power smaller than that of the first processor. In the electric device, power of the first processor is restricted through a restriction process in the power save operation mode. Further, in the power save operation mode, the second processor restricts the internal operation and processes the information input externally. When the second processor detects the information input externally, power of the first processor is released through a restriction releasing process.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
       [0001]    The present invention relates to an electric device capable of operating in a plurality of operation modes such as a normal operation mode (referred to as a normal mode) and a power save operation mode (referred to as a power save mode). 
         [0002]    A conventional electric device (for example, an image forming apparatus such as a printer) may be connected to a network (refer to Patent Reference). In the conventional electric device, an ASIC (Application Specific Integrated Circuit) constitutes a processor for a network processing. Accordingly, even when a main CPU (Central Processing Unit) is turned off, the processor for the network processing is capable of determining whether data are received or transmitted through the network (refer to Patent Reference). 
         [0003]    Patent Reference Japanese Patent Publication No. 2001-47693 
         [0004]    In the conventional electric device, when the processor for the network processing determines that data are received for performing a printing operation, an entire portion of the conventional electric device including the main processor is turned on. The processor for the network processing monitors a state of the network all the time, and is never turned off. Further, it is necessary to provide a processor in an engine of the image forming apparatus for an image processing. 
         [0005]    In the conventional electric device described above, it is necessary to provide a processor specifically for controlling an external interface as well. Accordingly, including a processor for a mechanical control, it is necessary to provide three processors, thereby increasing power consumption during a normal use. 
         [0006]    In view of the problems described above, an object of the present invention is to provide an electric device capable of solving the problems of the conventional electric device. 
         [0007]    Further objects and advantages of the invention will be apparent from the following description of the invention. 
       SUMMARY OF THE INVENTION 
       [0008]    In order to attain the objects described above, according to the present invention, an electric device is capable of operating in a normal operation mode (referred to as a normal mode) and a power save operation mode (referred to as a power save mode). The electric device includes a first processor for processing information input externally in the normal operation mode, and a second processor for processing an internal operation of the electric device in the normal operation mode. The second processor consumes power smaller than that of the first processor. 
         [0009]    In the electric device, power of the first processor is restricted through a restriction process in the power save operation mode. Further, in the power save operation mode, the second processor restricts the internal operation and processes the information input externally. When the second processor detects the information input externally, power of the first processor is released through a restriction releasing process. 
         [0010]    In the present invention, the second processor is provided for processing the internal operation of the electric device in the normal operation mode, and the second processor consumes power smaller than that of the first processor. In the power save operation mode, the second processor processes the information input externally. Through the restriction process, power of the first processor with larger power consumption or an unnecessary circuit portion is restricted or terminated. Accordingly, it is possible to reduce power consumption during an idle state of the electric device. Further, it is possible to continue to process the information input externally, thereby improving operability of the electric device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic view showing a block diagram showing a configuration of an electric device according to a first embodiment of the present invention; 
           [0012]      FIG. 2  is a flow chart showing a control operation of a sub-processor of the electric device in a power save mode according to the first embodiment of the present invention; 
           [0013]      FIG. 3  is a flow chart showing a control operation of a main-processor of the electric device according to the first embodiment of the present invention; 
           [0014]      FIG. 4  is a time chart showing a control operation of the electric device according to the first embodiment of the present invention; 
           [0015]      FIG. 5  is a schematic view showing a block diagram showing a configuration of an electric device according to a second embodiment of the present invention; and 
           [0016]      FIG. 6  is a flow chart showing a control operation of a main-processor of the electric device according to the second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0017]    Hereunder, embodiments of the present invention will be explained with reference to the accompanying drawings. Note that the accompanying drawings are shown only for an explanation purpose, and the present invention is not limited to the accompanying drawings. 
       First Embodiment 
       [0018]    A first embodiment of the present invention will be explained.  FIG. 1  is a schematic view showing a block diagram showing a configuration of an electric device  1  according to the first embodiment of the present invention. 
         [0019]    In the embodiment, the electric device  1  is an image forming apparatus (for example, an electro-graphic type page printer) having a power save mode. 
         [0020]    As shown in  FIG. 1 , the electric device  1  includes a first processor  2  (for example, a main processor). The main processor  2  is formed of a CPU (Central Processing Unit) for performing an interface control with respect to an external control device (for example, a host personal computer or a host PC) connected to the electric device  1  through a network (not shown), and for processing image data. 
         [0021]    As shown in  FIG. 1 , the main processor  2  is connected to an RAM  3  (Random Access Memory), an ROM  4  (Read Only Memory), and an image processing unit  5 . In the embodiment, the RAM  3  is an operational memory for the main processor  2  to process data, and the main processor  2  accesses to the RAM  3 . The ROM  4  is a memory for storing an instruction of the main processor  2 , and the main processor  2  accesses to the ROM  4 . 
         [0022]    In the embodiment, the main processor  2  controls the image processing unit  5 . In particular, the image processing unit  5  is formed of a circuit for performing a specific process on print data and the like received under control of the main processor  2 , so that the print data are converted to a printable format. Further, the image processing unit  5  is connected to an image forming unit  6 . The image forming unit  6  is formed of a mechanical unit including a motor and the like for forming an image on a recording medium (for example, a sheet) according to the printable data and an image forming processing unit for creating the image from an electrical signal. 
         [0023]    In the embodiment, the electric device  1  further includes a power source control unit  8 . In addition to a function of supplying power, the power source control unit  8  is capable of independently supplying and terminating power to the main processor  2 , the RAM  3 , the ROM  4 , the image processing unit  5 , the image forming unit  6 , and an inter-processor communication control unit  9  connected to the power source control unit  8  (represented within a hidden line). The inter-processor communication control unit  9  is connected between the main processor  2  and a second processor  11  (for example, a sub-processor  11 ), and the sub-processor  11  is connected to the image processing unit  5  through a network control unit  10 . 
         [0024]    In the embodiment, the inter-processor communication control unit  9  is formed of a circuit for controlling transmission and reception of a command and data between the main processor  2  and the sub-processor  11 . The network control unit  10  is formed of a circuit for controlling network connection with respect to the host PC (not shown). 
         [0025]    In the normal mode, the main processor  2  controls the network control unit  10 . In the power save mode, the sub-processor  11  controls the network control unit  10 . The sub-processor  11  is formed of a CPU (Central Processing Unit) having power consumption smaller than that of the main processor  2 . In the normal mode, the sub-processor  11  controls the image forming unit  6  (performs mechanical control of the electric device  1 ). In the power save mode, the sub-processor  11  controls the network control unit  10 . 
         [0026]    In the embodiment, the sub-processor  11  is connected to an RAM  12  and a switching control unit  13 . The switching control unit  13  is connected to a normal mode control program storage unit  14  and a power save mode control program storage unit  15 . The RAM  12  is an operational memory, and the sub-processor  11  accesses to the RAM  12 . 
         [0027]    In the embodiment, the switching control unit  13  is formed of a circuit for switching a command retrieved from the normal mode control program storage unit  14  or the power save mode control program storage unit  15  formed of an ROM for storing a command of the sub-processor  11 . In particular, the switching control unit  13  has a function of performing a switching operation according to an instruction of the main processor  2 . Further, the normal mode control program storage unit  14  is a memory for storing a control command of the sub-processor  11  in the normal mode, and the power save mode control program storage unit  15  is a memory for storing a control command of the sub-processor  11  in the power save mode. 
         [0028]    An entire operation of the electric device  1  shown in  FIG. 1  will be explained next. In the normal mode, the electric device  1  is connected to the host PC through the network. When the main processor  2  controls the network control unit  10  and receives the print data from the host PC through the network, the main processor  2  controls the image processing unit  5  to process the print data according to contents of the print data. 
         [0029]    When the image processing unit  5  creates the printable data (bit map data), the printable data are transmitted to the image forming unit  6 . The main processor  2  notifies the image forming unit  6  that the printable data are created through the inter-processor communication control unit  9 . According to the instruction of the main processor  2 , the sub-processor  11  controls the image forming unit  6  to perform a printing operation on the recording sheet. 
         [0030]    In the embodiment, when the electric device  1  does not receive the print data for a specific period of time, the main processor  2  starts a transition process for switching from the normal mode to the power save mode. More specifically, the main processor  2  sends an instruction to the sub-processor  11  to switch to the power save mode through the inter-processor communication control unit  9 . When the sub-processor  11  receives the instruction, the sub-processor  11  performs a process for turning off power of the image forming unit  6 . After the sub-processor  11  completes the process for turning off power of the image forming unit  6 , the sub-processor  11  sends a message to the main processor  2  that preparation is completed. 
         [0031]    When the main processor  2  receives the message that the preparation is completed, the main processor  2  resets the sub-processor  11  to switch the switching control unit  13  for retrieving a power same mode control program from the power save mode control program storage unit  15 . The power same mode control program stored in the power save mode control program storage unit  15  includes a process of performing a network process, a process of determining whether the print data are received and starting the main processor  2 , and a process of not starting the main processor  2  and processing by itself according to an access from the network (for example, a print status request) not related to the printing operation. 
         [0032]    In the embodiment, the sub-processor  11  performs the power save mode control program thus retrieved. More specifically, the sub-processor  11  sends an instruction to the power source control unit  8 , so that power of an unnecessary circuit is terminated in the power save mode. That is, power of the main processor  2 , the RAM  3 , the ROM  4 , the image processing unit  5 , the image forming unit  6 , and the inter-processor communication control unit  9  is terminated. In the power save mode, the sub-processor  11  performs various controls of the network through the network control unit  10 . Further, in the power save mode, when the electric device  1  receives the print data, the sub-processor  11  instructs the power source control unit  8  to supply power to all components. 
         [0033]    After the main processor  2  starts to become capable of processing the print data, the main processor  2  communicates with the sub-processor  11  through the inter-processor communication control unit  9  to take over the data processing of the network control unit  10 . When the main processor  2  takes over the data processing, the main processor  2  copies the print data thus received and remaining in the network control unit  10  to the Ram  3 . Further, the main processor  2  copies a parameter characteristic to the network (for example, an IP (Internet Protocol) address in the RAM  12 , an MAC (Media Access Control) address, an RAM address for storing link information connecting the network and received data, and the likes) to the RAM  3  administered with the main processor  2 , so that the main processor  2  can control the network control unit  10 . 
         [0034]    After the main processor  2  takes over all processes from the sub-processor  11 , the main processor  2  resets the sub-processor  11 . Further, the main processor  2  controls the switching control unit  13  to switch to the normal mode control program storage unit  14 . A normal mode control program stored in the normal mode control program storage unit  14  includes a process of controlling motor drive of the electric device  1  as a page printer, a process of controlling the printing operation (on/off control of a high voltage, control of a fixing device, and the like), a process of monitoring a state of the page printer, a process of monitoring a remaining amount of a consumable good such as a toner remaining amount, and the like. 
         [0035]    After the main processor  2  resets the sub-processor  11 , the sub-processor  11  retrieves the normal mode control program, and performs a process of controlling the image forming unit  6  in the normal mode. More specifically, the sub-processor  11  controls the image forming unit  6 , so that the image forming unit  6  receives the print data thus received from the image processing unit  5  to perform the printing operation, followed by discharging the recording sheet thus printed. 
         [0036]    A control operation of the sub-processor  11  of the electric device  1  in the power save mode will be explained next.  FIG. 2  is a flow chart showing the control operation of the sub-processor  11  of the electric device  1  in the power save mode according to the first embodiment of the present invention. 
         [0037]    In step S 1 , the sub-processor  11  starts the control operation of the power save mode. In step S 2 , the sub-processor  11  performs the take-over process with the main processor  2  for taking over information such as various settings of the current communication (for example, the IP address in the RAM  12 , the MAC address, the link information connecting to the network, the RAM address storing the received data, and the like). 
         [0038]    In step S 3 , the sub-processor  11  determines whether the sub-processor  11  receives the instruction of terminating power (the power termination instruction) from the main processor  2 . When the sub-processor  11  determines that the sub-processor  11  does not receive the power termination instruction from the main processor  2  (N), the process returns to step S 2 . When the sub-processor  11  determines that the sub-processor  11  receives the power termination instruction from the main processor  2  (Y), the process proceeds to step S 4 . 
         [0039]    In step S 4 , the sub-processor  11  instructs the power source control unit  8  to terminate power of the unnecessary circuits. In step S 5 , the sub-processor  11  controls the network control unit  10  to perform the network administration process. In step S 6 , the sub-processor  11  determines whether the print data are received from the network. When the sub-processor  11  determines that the print data are not received from the network (N), the process returns to step S 6  for continuously performing the network administration process. When the sub-processor  11  determines that the print data are received from the network (N), the process proceeds to step S 7 . 
         [0040]    In step S 7 , the sub-processor  11  controls and instructs the power source control unit  8  to supply power to all components of the electric device  1 . In step S 8 , the sub-processor  11  performs the take-over process with the main processor  2  for taking over the information of the current communication. The take-over process includes the print data received just before the take-over process. In step S 9 , the control process is completed. 
         [0041]    A control operation of the main-processor  2  of the electric device  1  will be explained next.  FIG. 3  is a flow chart showing the control operation of the main-processor  2  of the electric device  1  according to the first embodiment of the present invention. 
         [0042]    In step S 10 , the main processor  2  starts the control operation. In step S 11 , the main processor  2  determines whether the sub-processor  11  is in the power save mode. When the main processor  2  determines that the sub-processor  11  is in the power save mode (Y), the process proceeds to step S 13 . When the main processor  2  determines that the sub-processor  11  is not in the power save mode (N), the process proceeds to step S 12 . In step S 12 , the main processor  2  starts measuring an elapsed time since the main processor  2  starts the control operation, and the process proceeds to step S 14 . 
         [0043]    In step S 13 , the main processor  2  performs the take-over process with the sub-processor  11  for taking over the network control. In step S 14 , the main processor  2  controls the network control unit  10  to start the process of the network control with the host PC, and the process proceeds to step S 15 . In step S 15 , the main processor  2  determines whether the print data are received. When the main processor  2  determines that the print data are received (Y), the process proceeds to step S 16 . When the main processor  2  determines that the print data are not received (N), the process proceeds to step S 19 . 
         [0044]    In step S 16 , the main processor  2  sends the print data thus received to the image processing unit  5  to convert the print data to the printable data. In step S 17 , the image forming unit  6  performs the printing operation, and the process proceeds to step S 18 . In step S 18 , the main processor  2  starts measuring the elapsed time one more time from zero, and the process returns to step S 14 . 
         [0045]    In step S 19 , the main processor  2  determines whether a specific period of time is elapsed. When the main processor  2  determines that the specific period of time is elapsed (Y), the process proceeds to step S 20 . When the main processor  2  determines that the specific period of time is not elapsed (N), the process returns to step S 14 . 
         [0046]    In step S 20 , the main processor  2  performs the transition process to the power save mode. More specifically, the main processor  2  instructs the sub-processor  11  to terminate the control process of the image forming unit  6 . When the sub-processor  11  notifies the completion of the termination, the main processor  2  switches the switching control unit  13  from retrieving from the normal mode control program storage unit  14  to retrieving from the power save mode control program storage unit  15 . Then, the main processor  2  sets a reset signal of the sub-processor  11  to zero, and sets the reset signal to one after a specific period of time. 
         [0047]    In step S 21 , the main processor  2  determines whether the prosecuting program of the sub-processor  11  is switched to the power save mode. When the main processor  2  determines that the prosecuting program of the sub-processor  11  is switched to the power save mode (Y), the process proceeds to step S 22 . When the main processor  2  determines that the prosecuting program of the sub-processor  11  is not switched to the power save mode (N), the main processor  2  waits for the switching. 
         [0048]    In step S 22 , the main processor  2  sends the various information of the network control controlled in the main processor  2  to the sub-processor  11 , so that the network control is taken over, and the process proceeds to step S 23 . In step S 23 , after the main processor  2  completes the transition process to the power save mode, the main processor  2  instructs the sub-processor  11  to terminate power of the unnecessary circuits. In step S 24 , the control operation is completed. 
         [0049]    A control operation of the electric device  1  will be explained next.  FIG. 4  is a time chart showing the control operation of the electric device  1  according to the first embodiment of the present invention. 
         [0050]    In the time chart, a sequence of the operation is represented according to changes in signals. The sequence covers from when the electric device  1  is turned on to when the electric device  1  starts in the normal mode, the electric device  1  is switched to the power save mode, and the electric device  1  is returned to the normal mode. 
         [0051]    At timing T 1 , when the electric device  1  is turned on, the switching control unit  13  selects the normal mode control program storage unit  14 . Further, the main processor  2  performs the normal process and the sub-processor  11  performs the image forming unit control process. At timing T 2 , the main processor  2  starts measuring the elapsed time for switching to the power save mode. At timing T 3 , when the elapsed time reaches the specific period of time, the main processor  2  determines to switch to the power save mode. Accordingly, the main processor  2  sets a power save mode signal  2   a  to one, so that the main processor  2  starts the transition process to the power save mode. At this moment, the sub-processor  11  starts the termination process of the image forming unit  6 . 
         [0052]    At timing T 4 , when the sub-processor  11  notifies the main processor  2  that the transition process to the power save mode is completed, the main processor  2  sets a reset signal R of the sub-processor  11  to zero. At the same time, the main processor  2  switches the program to be retrieved with the sub-processor  11 . At timing T 5 , the main processor  2  sets the reset signal R of the sub-processor  11  to one. At this moment, the sub-processor  11  retrieves the program for the power save mode, and starts the network process. Further, the main processor  2  transmits the information for the network control to the sub-processor  11 . 
         [0053]    At timing T 6 , the main processor  2  determines that the sub-processor  11  completes the preparation of the network control process. Accordingly, the main processor  2  instructs the sub-processor  11  to terminate power to the unnecessary circuits. As a result, the sub-processor  11  sets a power termination signal  11   a  to one. 
         [0054]    At timing T 7 , power to the unnecessary circuits including the main processor  2  is terminated, and the sub-processor  11  starts the network process. At this moment, the main processor  2  is completely turned off, and the sub-processor  11  performs the network control in the power save mode. 
         [0055]    At timing T 8 , the sub-processor  11  determines that the data to be printed are received, and turns on the entire portion of the electric device  1 . At this moment, the main processor  2  starts the normal process. Further, the main processor  2  detects the state of the sub-processor  11 , and determines that the main processor  2  is returned from the power save mode. Accordingly, the main processor  2  exchanges the information for the network control with the sub-processor  11 , and the main processor  2  performs the control process of the network. 
         [0056]    At timing T 9 , the main processor  2  determines that the sub-processor  11  is capable of performing the image forming unit control process, and sets the reset signal R of the sub-processor  11  to zero. At the same time, the main processor  2  switches a program retrieval switch signal  2   b  to the retrieval of the normal mode control program. 
         [0057]    At timing T 10 , the main processor  2  sets the reset signal R of the sub-processor  11  to one. Accordingly, the sub-processor  11  retrieves the normal mode control program, and starts the image forming unit control process. When the image forming unit  6  is capable of performing the printing operation, the main processor  2  starts the printing operation of the data thus received. At timing T 11 , the main processor  2  starts measuring the elapsed time for the transition to the power save mode once again. 
         [0058]    As described above, in the first embodiment, the sub-processor  11  performs the control process of the image forming unit  6  in the normal mode. In the power save mode, the sub-processor  11  with low power consumption performs the network control process. Further, in the power save mode, the main processor  2  with large power consumption and the unnecessary circuits are turned off. Accordingly, it is possible to reduce power consumption of the electric device  1  during the idle time. Further, the sub-processor  11  performs the network control process, so that operability of the electric device  1  is improved. 
       Second Embodiment 
       [0059]    A second embodiment of the present invention will be explained next.  FIG. 5  is a schematic view showing a block diagram showing a configuration of an electric device  1 A according to the second embodiment of the present invention. Components in the second embodiment similar to those in the first embodiment are designated with the same reference numerals. 
         [0060]    As shown in  FIG. 5 , the electric device  1 A includes a cover switch  20  for detecting whether a cover of the image forming unit  6  opens. In the electric device  1 A, the sub-processor  11  monitors the cover switch  20  of the image forming unit  6  in the power save mode. When the cover of the image forming unit  6  does not open, it is possible to skip an initialization process of the image forming unit  6 , which is usually conducted, when the electric device  1 A is switched from the power save mode to the normal mode, thereby reducing a period of time for returning to the normal mode. 
         [0061]    More specifically, when the cover of the image forming unit  6  is opened, the cover switch  20  is turned on. The image forming unit  6  includes various image developing units. When developing toner does not have a sufficient amount, it is necessary to replace corresponding one of the image developing units. When the cover of the image forming unit  6  is opened to replace one of the image developing units, it is necessary to perform correction of color shift and various initialization processes. 
         [0062]    In the second embodiment, the cover switch  20  is turned on even in the power save mode, so that the sub-processor  11  monitors a state of the cover switch  20 . Accordingly, in the power save mode, when power of the image forming unit  6  is terminated, it is possible to store a history of opening and closing of the cover. As a result, it is possible to transmit the history to the main processor  2  upon returning to the normal mode. Other configurations of the electric device  1 A are similar to those of the electric device  1  in the first embodiment. 
         [0063]    A control operation of the main-processor  2  of the electric device  1 A will be explained next.  FIG. 6  is a flow chart showing the control operation of the main-processor  2  of the electric device  1 A according to the second embodiment of the present invention. Steps in the second embodiment similar to those in the first embodiment are designated with the same reference numerals. 
         [0064]    In the flow chart shown in  FIG. 6 , steps S 31  and S 32  are inserted between step S 13  to step S 12  of the flow chart shown in  FIG. 3 . Only difference of the control operation of the main processor  2  from the first embodiment will be explained. 
         [0065]    After the main processor  2  exchanges the network control with the sub-processor  11  in step S 13 , the process proceeds to step S 31 . In step S 31 , the main processor  2  retrieves the history information of the cover switch  20  of the image forming unit  6  from the sub-processor  11 , so that the main processor  2  determines whether the cover is opened. When the main processor  2  determines that the cover is opened (Y), the process proceeds to step S 12 . When the main processor  2  determines that the cover is not opened (N), the process proceeds to step S 32 . In step S 32 , the main processor  2  instructs the sub-processor  11  not to perform the initialization process of the image forming unit  6 , and the process proceeds to step S 12 . The process after step S 12  is the same as that in the first embodiment. 
         [0066]    As described above, in the second embodiment, the sub-processor  11  monitors the cover switch  20  of the image forming unit  6  in the power save mode. According to the opening history of the cover, the initialization process of the image forming unit  6  is not conducted, when the electric device  1 A is switched from the power save mode to the normal mode, thereby reducing a period of time for returning to the normal mode. Further, it is possible to form a proper image all the time, thereby improving operability of the electric device  1 A. 
         [0067]    The present invention is not limited to the first and second embodiments, and may be modified as follows. 
         [0068]    The configurations of the electric device  1  and the electric device  1 A shown in  FIGS. 1 and 5  may be modified. Further, the control operations shown in  FIGS. 2 to 4  and  6  may be modified. 
         [0069]    In the first and second embodiments, the electric device  1  and the electric device  1 A are explained as the image forming apparatus. The present invention is applicable to other image forming apparatus such as a facsimile, a copier, a multi-function product, and the like. In this case, it is possible to obtain an effect similar to those in the first and second embodiments. 
         [0070]    The disclosure of Japanese Patent Application No. 2009-147480, filed on Jun. 22, 2009, is incorporated in the application by reference. 
         [0071]    While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.