Patent Publication Number: US-2015085313-A1

Title: Information processing apparatus and method for controlling the same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     One disclosed aspect of the embodiments relates to an information processing apparatus for controlling a power state, and a method for controlling the information processing apparatus. 
     2. Description of the Related Art 
     An image forming apparatus having a print function, a scanning function, and a fax function, such as a multifunction peripheral (MFP) or a printer, is provided with an energy-saving mode for reducing power consumption when the apparatus is not in use. For example, a certain image forming apparatus mounts a human body detection sensor to improve user&#39;s convenience when returning from the energy-saving mode. This type of image forming apparatus has advantages that user&#39;s button operations can be omitted, and that the apparatus can return from the energy-saving mode quicker than with button operations. However, since there is a possibility to incorrectly detect a person who does not intend to operate the image forming apparatus, it is necessary to reduce the possibility of false detection. 
     As a first example, Japanese Patent Application Laid-Open No. 2006-313407 discusses an image forming apparatus which, to reduce the possibility of false detection, first detects a human body (moving object) and monitors the motion of the detected human body. Then, if the image forming apparatus has kept human body detection for a predetermined time period, it determines that a user has approached the apparatus, and returns from the energy-saving mode. 
     As a second example, a certain image forming apparatus detects a human body by using a low-accuracy pyroelectric sensor providing low power consumption. After the detection of a human body, the image forming apparatus turns ON the power of a reflection type sensor capable of high-accuracy human body detection with high power consumption, and, at the timing when the possibility of false detection becomes low, determines that a user has approached the apparatus. 
     Although both of the above-described examples are effective in reducing the possibility of false detection, they have a problem that detection takes time. This problem is disadvantageous in shortening the return time which is one of advantages of using the human body detection method. 
     The second example has a problem that, in the case of false detection, the reflection type sensor providing high power consumption uselessly consumes power. 
     SUMMARY OF THE INVENTION 
     A disclosed aspect of the embodiments is directed to providing a mechanism for restricting power generation processing in a case where, even after power generation starts upon detection of a factor to lead a second power state to be canceled, the factor to lead the second power state to be canceled is not maintained. 
     According to an aspect of the embodiments, an information processing apparatus includes a first control unit, a first detection unit configured to detect a person, a generation unit configured to generate power to be supplied to the control unit when a person is detected by the first detection unit, a determination unit configured to determine whether the person detected by the first detection unit is a user of the information processing apparatus, and a second control unit configured to, when the determination unit determines that the person detected by the first detection unit is a user of the information processing apparatus, perform control to supply the power generated by the generation unit to the first control unit. 
     Further features of the disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a configuration of an example system including an image forming apparatus. 
         FIG. 2  is a block diagram illustrating an internal configuration of an MFP illustrated in  FIG. 1 . 
         FIG. 3  illustrates a range of human body detection by the MFP, and a position of a human body. 
         FIG. 4  is a block diagram illustrating an internal structure of a human body detection unit illustrated in  FIG. 2 . 
         FIG. 5  is a block diagram illustrating a configuration of a control unit illustrated in  FIG. 2 . 
         FIG. 6  is a block diagram illustrating a configuration of a local power source unit. 
         FIG. 7  is a block diagram illustrating a configuration of a switch unit illustrated in  FIG. 5 . 
         FIG. 8  is a timing chart illustrating an example operation of the switch unit illustrated in  FIG. 7 . 
         FIG. 9  is a timing chart illustrating power outputs and control signals. 
         FIG. 10  is a flowchart illustrating a method for controlling the image forming apparatus. 
         FIG. 11  is a block diagram illustrating a configuration of the image forming apparatus. 
         FIG. 12  is a timing chart illustrating operations of the image forming apparatus illustrated in  FIG. 11 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Various exemplary embodiments, features, and aspects of the disclosure will be described in detail below with reference to the drawings. 
     An image forming apparatus according to a first exemplary embodiment starts power supply in advance during a wait time for false detection prevention to quickly return from an energy-saving mode. 
       FIG. 1  is a configuration of an example system including an image forming apparatus according to the present exemplary embodiment. 
     Referring to  FIG. 1 , MFPs  104  and  105 , a printer  106 , and a fax  107  are connected to a network  101 . In this case, Ethernet (registered trademark) is used as the network  101 . The image forming apparatus according to the present exemplary embodiment is provided with a function of performing power control in a first power state and in a second power state in which the apparatus provides lower power consumption than in a first power state. 
     Since the disclosure is not dependent on a network format, it is also applicable to other network systems. The MFPs  104  and  105  are devices having copy, printer, and scanner functions in an integrated way. There are variations in color printing and printing speed. The printer  106  and the fax  107  are single-function apparatuses. Personal computers (PCs)  102  and  103  are user&#39;s PCs capable of performing printing operations, scanning operations, and fax transmitting operations by transmitting/receiving data to/from the MFPs  104  and  105 , the printer  106 , and the fax  107  connected to the network  101 . 
     The configuration and operations of the MFP  104  will be described below. Although the embodiment is also applicable to the MFP  105 , the printer  106 , and the fax  107 , it will be described below based on the MFP  104  to simplify descriptions. 
       FIG. 2  is a block diagram illustrating an internal configuration of the MFP  104  illustrated in  FIG. 1 . 
     Referring to  FIG. 2 , a control unit  202  controls operations of the MFP  104  to perform data transmission and reception, data conversion, data storage, and power control. When the MFP  104  performs print operations, job data is generated by the PC  102 , transmitted to the control unit  202  via the network  101 , and then once stored in the control unit  202 . The control unit  202  converts the stored job data into image data, and transmits it to a printer unit  204 . The printer unit  204 , under control of the control unit  202 , prints the image data on recording paper (sheet) and discharges it to the outside of the apparatus. 
     When the MFP  104  performs scanning operations, the user sets a document onto a scanner unit  203 , performs button operations referring to a screen of an operation unit  201  to set scanning operations, and instructs to start scanning operations. The scanner unit  203 , under control of the control unit  202 , optically reads the document, and converts it into image data. The image data is once stored in the control unit  202 . Then, the control unit  202  transmits the image data to a transmission destination specified from the operation unit  201  in advance. 
     When the MFP  104  performs copy operations, the user sets a document onto the scanner unit  203 , performs button operations referring to the screen of the operation unit  201  to set copy operations, and instructs to start copy operations. The scanner unit  203 , under control of the control unit  202 , optically reads the document, and converts it into image data. The image data is once stored in the control unit  202 . Then, the control unit  202  converts the image data into a data format usable by the printer unit  204 . The printer unit  204  prints the image data on a sheet, and discharges it to the outside of the apparatus. 
     A first power source  205  and a second power source  207  function as a power source unit for converting alternating-current (AC) commercial power supplied from a power plug  206  into a direct-current (DC) voltage to be used by each unit of the MFP  104 . The second power source  207  is subjected to power output control by a power source control signal  208  output from the control unit  202 . 
     In a normal mode (a mode of the first power state) for performing image formation processing, the first power source  205  is turned ON. In the energy-saving mode (a mode of the second power state) in which the apparatus provides lower power consumption than in the first power state, the first power source  205  is turned OFF. 
     The energy-saving mode is a mode in which, while the apparatus does not performing job processing, power supply to portions other than the control unit  202  stops to reduce the power consumption of commercial power. In the energy-saving mode, the control unit  202  can detect job reception, and a human body detection unit  210  can detect a human body based on an output signal from a human body detection sensor  209 . In a state where there is a possibility of false detection, the human body detection unit  210  asserts a signal indicating human body detection. Then, power supply to each circuit starts. 
     The control unit  202  includes a switch unit on a power line. Turning OFF the switch unit interrupts power supply to each circuit of the control unit  202 . Although the power consumption slightly increases by starting power supply under a no-load condition, the power consumption is very small in comparison with that during a normal operation. When a human body detection state continues for a predetermined time period, the human body detection unit  210  asserts a human body detection return trigger signal  212 , and turns ON the switch unit in the control unit  202  to start power supply to each circuit. In a case of false detection, by negating a human body detection signal  211  in a state where the human body detection return trigger signal  212  is not asserted, the power consumption in a normal energy-saving mode can be immediately restored. If power supply is turned ON to activate each circuit of the control unit  202  at the time of false detection, the control unit  202  needs to reliably perform activation processing and shutdown processing. As a result, the control unit  202  will continue a high power consumption state for a prolonged time period. 
       FIG. 3  illustrates a range of human body detection by the MFP  104 , and the position of a human body. 
     In the present exemplary embodiment, the human body detection sensor  209  is provided on a front face of the MFP  104 . Since the human body detection sensor  209  is a pyroelectric sensor, the human body can be detected in a certain amount of width and distance, as indicated by a human body detection area  301 . 
     When the human body exists at a first position  302 , the human body detection unit  210  asserts the human body detection signal  211 . Then, the human body detection unit  210  maintains the human body detection state until the human body moves to a second position  303  after a predetermined time period has elapsed. At this timing, the human body detection unit  210  asserts the human body detection return trigger signal  212  illustrated in  FIG. 2 . To reduce the possibility of false detection, it is necessary to wait for a predetermined time period. 
       FIG. 4  is a block diagram illustrating an internal structure of the human body detection unit  210  illustrated in  FIG. 2 . 
     Referring to  FIG. 4 , the human body detection unit  210  performs signal level amplification and filtering for noise elimination on an output signal of the human body detection sensor  209  by using a sensor I/F  401 , and outputs the signal to a human body detection control unit  402 . The human body detection control unit  402  determines the human body detection state based on a signal input from the sensor I/F  401 . When the human body detection control unit  402  recognizes the human body detection state, it asserts the human body detection signal  211 . 
     To determine whether the human body is a passer-by or a person (operator) who intends to operate the MFP  104 , the human body detection control unit  402  checks whether the human body detection is to be continued for a predetermined time period by using a timer. When a predetermined time period has elapsed since a human body was first detected, the human body detection control unit  402  asserts the human body detection return trigger signal  212 . 
       FIG. 5  is a block diagram illustrating a configuration of the control unit  202  illustrated in  FIG. 2 . 
     Referring to  FIG. 5 , a central processing unit (CPU)  502  for controlling the control unit  202  reads a program from a low-speed nonvolatile memory  506 , writes the program to a high-speed volatile memory  507 , and executes the program on the volatile memory  507 . The volatile memory  507  is used also as a temporarily storage area. A network I/F unit  501  for performing network communication, a scanner I/F  503  for communicating with the scanner unit  203 , and a printer I/F  505  for communicating with the printer unit  204  are connected each other via an internal bus  508 . An operation unit I/F  504  performs input/output processing between the operation unit  201  and the CPU  502 . 
     When the MFP  104  is in the energy-saving mode, the output of the second power source  207  is turned OFF by the power source control signal  208  output from the control unit  202 . At this timing, only the network I/F unit  501  and a starting trigger generation unit  509  are operating in the control unit  202  since they receives power supply from the first power source  205 . 
     One shift trigger for shifting from the energy-saving mode to the normal state is reception of a wake packet via the network  101 . The network I/F unit  501  refers to the contents of a received packet, and, when it determines that the packet needs to be processed, such as job data, it asserts a network return trigger signal  511 . Another shift trigger for shifting from the energy-saving mode to the normal state is detection by the human body detection unit  210  that a user has approached the MFP  104  to operate it. 
     When the human body detection signal  211  is asserted, the starting trigger generation unit  509  asserts the power source control signal  208  for activating the second power source  207 . At this timing, the second power source  207  starts outputting 12 V, and the local power source unit  510  for generating power having different power potential levels starts outputting 3.3 V, 1.8 V, and 1.0 V. However, while the human body detection return trigger signal  212  is in a negate state, the outputs of the local power source unit  510  are interrupted by a switch unit  515 . Therefore, since power is not supplied to each circuit, none of circuits is activated. When the human body detection return trigger signal  212  is asserted, the starting trigger generation unit  509  asserts an operation control signal  514 . When the operation control signal  514  is input to the switch unit  515 , the switch unit  514  changes to the connecting state to start power supply to each circuit of the control unit  202 , and negates a second reset signal  516 . Then, the circuits of the control unit  202  start operating. A first reset signal  512  is input to the switch unit  515  from the local power source unit  510 . The first reset signal  512  will be described below. 
     When no print, copy, or fax job is executed, and no user operation is performed on the operation unit  201  in the normal mode, the CPU  502  shifts to the energy-saving mode. To shift to the energy-saving mode, the CPU  502  performs processing for shutting down the operating system (OS) and processing for deactivating each unit, and then controls the power source control signal  208  to turn OFF the second power source  207 . 
       FIG. 6  is a block diagram illustrating a configuration of the local power source unit  510  in a conventional case. 
     Referring to  FIG. 6 , the local power source unit  510  outputs three different power voltages (3.3 V, 1.8 V, and 1.0 V) from the 12-V power output from the second power source  207 , and outputs the first reset signal  512  indicating that these three power outputs are stable. 
     A 12-V power good signal generation unit  601  for generating 12 Volts of direct current (VDC) is a circuit for detecting whether 12-V power from the second power source  207  reaches a prescribed value or higher. When 12-V power reaches the prescribed value or higher, the 12-V power good signal generation unit  601  asserts a 12-V power good signal  602 . Regularly, a delay time is provided before asserting the power good signal  602  in consideration of a time duration until the signal becomes stable. The 12-V power good signal  602  is ANDed (logical product) with the power source control signal  208 . The resultant output is input to the enable terminal of a 3.3-V generation unit  603 . When starting power supply, the local power source unit  510  activates the 3.3-V generation unit  603  after the 12-VDC output of the second power source  207  becomes stable. 
     When turning power OFF, the starting trigger generation unit  509  illustrated in  FIG. 5  immediately negates the power source control signal  208 , and the output of the 3.3-V generation unit  603  is turned OFF. When starting power supply, power supply sequentially starts with a margin by using a delay circuit to achieve stable operations. When turning power supply OFF, power supply to all circuits is simultaneously turned OFF to prevent degradation of the circuit reliability. However, it is necessary to perform timing design within a range in which specifications of semiconductor devices used in the control unit  202  are satisfied. 
     A 3.3-V power good signal generation unit  604  is a circuit for monitoring the output voltage of the 3.3-V generation unit  603 . When starting power supply, the 3.3-V power good signal generation unit  604  asserts a 3.3-V power good signal  605  after providing a predetermined delay time, similar to the 12-V power good signal generation unit  601 . The power good signal  605  asserted by the 3.3-V power good signal generation unit  604  activates a 1.8-V generation unit  606 . Likewise, a power good signal  608  asserted by a 1.8-V power good signal generation unit  607  activates a 1.0-V generation unit  609 . A 1.0-V power good generation unit  610  monitors the output voltage of the 1.0-V generation unit  609 . The output voltage of the 1.0-V power good generation unit  610  is ANDed with the power source control signal  208 . The resultant output, as the first reset signal  512 , is connected to each circuit of the control unit  202 . 
       FIG. 7  is a block diagram illustrating a configuration of the switch unit  515  illustrated in  FIG. 5 . 
     Referring to  FIG. 7 , 3.3-V power, 1.8-V power, and 1.0-V power output from the local power source unit  510  are input to a 3.3-V switch unit  701 , a 1.8-V switch unit  704 , and a 1.0-V switch unit  707 , respectively. Outputs of these switch units are supplied to other circuits. 
     When the operation control signal  514  is asserted, the 3.3-V switch unit  701  is first connected. The output of the 3.3-V switch unit  701  is supplied to other circuits of the control unit  202 , and input to a 3.3-V switch power good signal generation unit  702 . When the output of the 3.3-V switch unit  701  is equal to or higher than a prescribed voltage, a 3.3-V switch power good signal  703  is asserted and the 1.8-V switch unit  704  is connected. 
     Likewise, the output voltage of the 1.8-V switch unit  704  enables a 1.8-V switch power good signal generation unit  705  to generate a 1.8-V switch power good signal  706 . Then, the 1.0-V switch unit  707  is connected. The output voltage of the 1.0-V switch unit  707  enables a 1.0-V switch power good signal generation unit  708  to generate a 1.0-V switch power good signal  709 . The power good signal for each switch unit is ANDed with the operation control signal  514 . Therefore, when the operation control signal  514  is negated, power supply to all circuits is turned OFF, and the reset signal is asserted. 
     The power good signal  709  of the 1.0-V switch power good signal generation unit  708  is ANDed with the operation control signal  514 . The resultant, i.e., an internal reset signal  710  is further ANDed with the first reset signal  512 . The resultant is connected, as the second reset signal  516 , to each circuit of the control unit  202 . 
     This configuration is used when the negation of the internal reset signal  709  is earlier than the negation of the first reset signal  512 . In this case, any one voltage of the local power source unit  510  is not output, or the delay time of the first reset signal  512  has not yet elapsed. Since the second reset signal  516  is negated simultaneously with or after the first reset signal  512 , the internal reset signal  710  and the first reset signal  512  are output as the second reset signal  516  via an AND circuit. 
       FIG. 8  is a timing chart illustrating an example operation of the switch unit  515  illustrated in  FIG. 7 . This example indicates waveforms of power outputs and control signals when starting power supply according to the first exemplary embodiment. The power source control signal  208  is a high active signal which means power ON in the high-level state, and means power OFF in the low-level state. The local power source unit  510  according to the present exemplary embodiment sequentially determines generation of power having different power levels, and generates power having a plurality of power levels, in response to determination to generate power having one power level at the timing described below. 
     The first reset signal  512  is a low active signal which resets the circuit in the low-level state, and activates the circuit in the high-level state. The 12-V power good signal  602 , the 3.3-V power good signal  605 , and the 1.8-V power good signal  608  are high active signals which mean power output in the high-level state, and mean non-power output or an output voltage lower than the prescribed value in the low-level state. 
     As described above, when the power source control signal  208  is asserted, 12-V power is output from the second power source  207 . When a delay time T801 has elapsed since a certain voltage is reached, the 12-V power good signal  602  is asserted. Hereinafter, the 3.3-V power good signal  605  provides a delay time T802, the 1.8-V power good signal  608  provides a delay time T803, and the 1.0-V power output provides a delay time T804. 
     To initialize an internal clock of the CPU  502  and each circuit, the delay time T804 needs to be longer than the delay time T802 and the delay time T803. A wait time T806 necessary for the voltage of the second power source  207  to rise is longer than that for other power outputs. There are many portions to which the second power source  207  can supply power, resulting in a large load. Therefore, if the voltage of the second power source  207  quickly rises, an inrush current increases and activation processing fails. 
     A total time period T805 indicates a time period since the power source control signal  208  is asserted until the first reset signal  512  is asserted. The total time period T805 is a part of operations of the MFP  104  for returning from the energy-saving mode. Shortening the total time period T805 enables reducing user&#39;s stress for waiting for activation. 
     The output of each switch is prevented until the operation control signal  514  is asserted. After the operation control signal  514  is asserted, the 3.3-V switch unit  701 , the 1.8-V switch unit  704 , and the 1.0-V switch unit  707  are sequentially connected in this order. Referring to  FIG. 8 , respective power good signals provide delay times T807, T808, and T809. A time period T810 since the operation control signal  514  is asserted until the second reset signal  516  is asserted can be made shorter than the total time period T805. The return time is shortened by the difference between the time period T810 and the total time period T805, in comparison with a conventional case in which power supply does not start through human body detection. 
       FIG. 9  is a timing chart illustrating power outputs and control signals when the image forming apparatus according to the present exemplary embodiment shifts to the energy-saving mode. 
     When the image forming apparatus shifts to the energy-saving mode, the CPU  502  determines shift conditions, shuts down the system when shift conditions are satisfied, and, when shutdown is completed, asserts a shutdown request signal  513 . At this timing, the starting trigger generation unit  509  negates the power source control signal  208 . Then, the starting signal of the power generation circuit of the local power source unit  510  is negated, and each power output turns OFF. Further, the first reset signal  512  is also negated. 
       FIG. 10  is a flowchart illustrating a method for controlling the image forming apparatus according to the present exemplary embodiment. This example indicates processing by the human body detection unit  210  illustrated in  FIG. 2 . Each step is implemented when the human body detection control unit  402  illustrated in  FIG. 4  executes a control program stored in the internal memory. Hereinafter, when the human body detection unit  210  changes to a first state where an object (the body of the user operating the image forming apparatus) is detected, the human body detection control unit  402  controls a power generation unit for shifting from the second power state to the first power state to start power generation. The following describes example processing for restricting supplying the power generated by the power generation unit to the control unit  202  when the human body detection unit  210  changes from the first state where an object is detected to a second state where no object is detected. 
     In step S 1001 , the human body detection control unit  402  negates the human body detection signal  211  and the human body detection return trigger signal  212 . In step S 1002 , the human body detection control unit  402  waits until the human body detection sensor  209  detects a human body (object). When the human body is determined to have been detected (YES in step S 1002 ), then in step S 1003 , the human body detection control unit  402  asserts the human body detection signal  211 . As described above, when the human body detection control unit  402  asserts the human body detection signal  211 , the starting trigger generation unit  509  asserts the power source control signal  208 , and the second power source  207  starts power output. In step S 1004 , the CPU  502  of the control unit  202  initializes an internal timer (not illustrated) for reducing false detection to start count processing. 
     In step S 1005 , the CPU  502  of the control unit  202  determines whether the timer which started the above-described count processing has counted a predetermined time period. When the CPU  502  determines that the predetermined time period has been counted (YES in step S 1005 ), it determines that the human body detected by the human body detection sensor  209  is a user who intends to operate the MFP  104 , and the processing proceeds to step S 1006 . 
     In step S 1006 , to return the image forming apparatus from the energy-saving mode (low power state), the CPU  502  of the control unit  202  asserts the human body detection return trigger signal  212 , and ends the processing for returning to the normal power state. 
     On the other hand, when the CPU  502  determines that the predetermined time period has not been counted (NO in step S 1005 ), then in step S 1007 , the CPU  502  determines whether human body detection is output from the human body detection sensor  209 . When the CPU  502  determines that human body detection is output (YES in step S 1007 ), it repeats the processing from step S 1005 . On the other hand, when the CPU  502  determines human body detection is not output (NO in step S 1007 ), it determines that the object is a passer-by who passes the image forming apparatus, then in step S 1008 , the CPU  502  negates the human body detection signal  211 . At this timing, the starting trigger generation unit  509  negates the power source control signal  208  to turn OFF the second power source  207  and the local power source unit  510 . Then, the CPU  502  returns processing to step S 1002 , and waits for human body detection. 
     According to the present exemplary embodiment, the switch unit  515  is provided between the local power source unit  510  and the CPU  502 . Using the human body detection signal  211  and the human body detection return trigger signal  212  enables quickly returning from the energy-saving mode. 
     Even in a case of false human body detection, the power increase can be reduced, and power supply can be immediately turned OFF at the timing when false detection is determined. Further, even in a state where power supply is turned ON, the power consumption slightly increases since there is no power load. 
     Although, in the present exemplary embodiment, each switch is turned ON when the relevant human body detection return trigger is asserted, the same effect can be obtained even when a DC/DC voltage conversion circuit is used instead of a switch. When the DC/DC voltage conversion circuit is used, for example, the local power source unit  510  described in the first exemplary embodiment is not necessary, and the output of the second power source  207  is connected to the input of the DC/DC voltage conversion circuit. 
     When a trigger input other than human body detection, for example, a network return trigger signal  311 , is asserted, the image forming apparatus can be returned from the sleep state by simultaneously asserting the power source control signal  208  and the operation control signal  514 . 
     The present exemplary embodiment is also applicable to return triggers other than human body detection, for example, a return from the energy-saving mode upon reception of a network packet. In the case of network packet reception, for example, control is performed in such a way that power supply is turned ON upon reception of a packet, and the switch unit  515  is turned ON when the network I/F unit  501  determines that power supply should start based on the contents of the packet. 
     Different sensors may be used for a first trigger and a second trigger. For example, as described in “Description of Related Art”, it is also applicable to an example in which a pyroelectric sensor and a reflection type sensor are used together to detect a human body. A pyroelectric sensor is used as the first trigger, and a reflection type sensor as the second trigger. 
     A second exemplary embodiment will be described below based on an example in which the power increase is reduced by deactivating each circuit by asserting the reset signal even in a case where power is supplied to each circuit of the control unit  202 . In the present exemplary embodiment, after a predetermined time period has elapsed since the human body detection sensor  209  detected an object, if the MFP  104  shifts to a state where the object is not detected, the MFP  104  resets the control unit  202  and performs power source control for shifting to a third power state while continuing power generation processing. 
       FIG. 11  is a block diagram illustrating a configuration of the image forming apparatus according to the present exemplary embodiment. This example corresponds to another example configuration of the control unit  202 . The configuration of the present exemplary embodiment differs from that of the first exemplary embodiment in that a reset generation circuit  1101  is provided instead of the switch unit  515 . 
     Referring to  FIG. 11 , the reset generation circuit  1101  is an AND circuit for the operation control signal  514  (described in the first exemplary embodiment) and the first reset signal  512  output by the local power source unit  510 . The reset generation circuit  1101  generates a third reset signal  1102  which is input to each circuit of the control unit  202  as a reset signal. 
     The above-described configuration enables performing control in such a way that power supply to each circuit starts after the power source control signal  208  is asserted, and, if the operation control signal  514  is not asserted after the first reset signal  512  is negated, the third reset signal  1102  is not negated. Specifically, since each circuit of the control unit  202  does not operate, the control unit  202  consumes less power than it does during operation. Then, when the operation control signal  514  is negated, the third reset signal  1102  is negated, and the control unit  202  immediately starts operation. 
       FIG. 12  is a timing chart illustrating operations of the image forming apparatus illustrated in  FIG. 11 . This example corresponds to the timing of power outputs and control signals when the image forming apparatus shifts to the energy-saving mode. As illustrated in  FIG. 11 , the third reset signal  1102  is the logical product (AND) of the operation control signal  514  and the first reset signal  512 . Since the third reset signal  1102  is negated at the same time when the operation control signal  514  is negated, the starting time can be zeroed. 
     According to the present exemplary embodiment, the power increase can be reduced by deactivating each circuit by asserting each reset signal even in a case where power is supplied to each circuit of the control unit  202 . Since the time required to start power supply can be zeroed, the present exemplary embodiment provides more profound effect of quickly returning from the sleep time than that in the first exemplary embodiment. 
     Although, in the second exemplary embodiment, a reset signal is used as a signal for deactivating operations of each circuit in a state where power is supplied to each circuit of the control unit  202 , other signals, for example, a signal for stopping the clock may be used. 
     Therefore, according to each exemplary embodiment, even if power generation starts upon detection of a factor on which the second power state should be canceled, the power generation processing can be restricted if the factor on which the second power state should be canceled is not maintained. Further, even if power generation starts upon detection of the factor on which the second power state should be canceled, the power-saving state can be continued by keeping preventing the control unit  202  from starting control processing. 
     Each process of the embodiments can also be implemented when software (program) acquired via a network or various storage media is executed by a processing apparatus (a CPU or a processor) in a PC (computer). 
     The disclosure is not limited to the above-described exemplary embodiments, and can be modified in diverse ways (including organic combinations of these exemplary embodiments) without departing from the spirit and scope thereof. These modifications are not excluded from the scope of the disclosure. 
     According to the disclosure, even power generation starts upon detection of a factor on which the second power state should be canceled, the power generation processing can be restricted if the factor on which the second power state should be canceled is not maintained. 
     Embodiments of the disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions recorded on a storage medium (e.g., non-transitory computer-readable storage medium) to perform the functions of one or more of the above-described embodiment(s) of the disclosure, and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more of a central processing unit (CPU), micro processing unit (MPU), or other circuitry, and may include a network of separate computers or separate computer processors. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like. 
     While the disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2013-200060 filed Sep. 26, 2013, which is hereby incorporated by reference herein in its entirety.