Abstract:
An image-reading device is provided that includes a reading component configured to read a document, a document holding portion, a detector detecting a position of the document holding portion, a power supply device that supplies power to the reading component, and a power supply control device that controls power supplied by the power supply device to the reading component. The power supply control device determines whether a change in the position of the document holding portion has occurred based on the position of the document holding portion detected by the detector. When a change in position is detected and the image reading device is not performing document reading, the power supplied to the reading component is reduced. If a change in position is detected while the image reading device is performing document reading, the power supplied to the reading component is maintained.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Japanese Patent Application No. 2011-286379, filed on Dec. 27, 2011 and Japanese Patent Application No. 2012-096788, filed on Apr. 20, 2012, which are incorporated herein by reference. 
       FIELD 
       [0002]    The disclosure relates to an image-reading device that reads a document, and more specifically, to an image-reading device that controls power supply to reduce power consumed by reading components used for document reading. 
       BACKGROUND 
       [0003]    In order to achieve power savings, a known image-reading device, for example, a scanner, is configured to enter a power saving mode to reduce power consumed by reading components used for document reading while the scanner is not in an operating condition. 
         [0004]    A known scanner, as an example of an image-reading device that controls power, includes a retractable document mount that is capable of opening and closing with respect to a main body of the known scanner. The known scanner is configured to turn itself on or off in accordance with the opening or closing of the document mount. 
       SUMMARY 
       [0005]    The known scanner is configured to turn itself on or off in accordance with opening or closing of the document mount. When the document mount is changed to an unused position during document reading, the known scanner turns itself off during the document reading and this may detrimentally influence image reading quality. The configuration in which turning on or off of power of the known scanner is controlled by the opening or closing of the document mount provides usability. Thus, the scanner not having such a configuration may reduce user convenience. 
         [0006]    According to aspects of the disclosure, an image-reading device configured to control power supply and achieve image-reading quality and user convenience may be accomplished. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    For a more complete understanding of the present disclosure and the features and advantages thereof, reference now is made to the following descriptions taken in connection with the accompanying drawing. 
           [0008]      FIG. 1  depicts a scanner in an illustrative embodiment according to one or more aspects of the disclosure, wherein a document feed tray is closed. 
           [0009]      FIG. 2  depicts the scanner in the illustrative embodiment according to one or more aspects of the disclosure, wherein the document feed tray is opened. 
           [0010]      FIG. 3  depicts an internal configuration of the scanner of  FIG. 1  in the illustrative embodiment according to one or more aspects of the disclosure. 
           [0011]      FIG. 4  depicts the internal configuration of the scanner of  FIG. 2  in the illustrative embodiment according to one or more aspects of the disclosure. 
           [0012]      FIG. 5  is a block diagram depicting an electric configuration of the scanner in the illustrative embodiment according to one or more aspects of the disclosure. 
           [0013]      FIG. 6  is a perspective view depicting a power supply control system in the illustrative embodiment according to one or more aspects of the disclosure. 
           [0014]      FIG. 7  depicts a relationship between each mode and a condition of power supply to each component in the illustrative embodiment according to one or more aspects of the disclosure. 
           [0015]      FIG. 8  is a flowchart depicting a mode switching process in the illustrative embodiment according to one or more aspects of the disclosure. 
           [0016]      FIG. 9  is a flowchart depicting a second power-saving mode executing process in the illustrative embodiment according to one or more aspects of the disclosure. 
           [0017]      FIG. 10  is a flowchart depicting a power saving mode switching process in the illustrative embodiment according to one or more aspects of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Hereinafter, an illustrative embodiment in which an image-reading device according to the aspects of the disclosure may be implemented is described in detail with reference to the accompanying drawings. In the illustrative embodiment, the aspects of the disclosure may be applied to a scanner that may have a power saving mode for reducing power consumption in the scanner. 
         [0019]    As depicted in  FIGS. 1 and 2 , a scanner  100  may comprise a housing  6 , a document holding portion such as a document feed tray  91 , and a document discharge tray  92 . Housing  6  may cover a main body of scanner  100 . Document feed tray  91  may be configured to cover or uncover an upper surface  6 A of housing  6  and be opened or closed with respect to scanner  100 . Document discharge tray  92  may be disposed at a lower part of scanner  100 . In  FIG. 1 , the side on which document discharge tray  92  may be disposed may be defined as the front of scanner  100 . The right, left, front, and rear of scanner  100  may be defined when scanner  100  is disposed in an orientation in which it is intended to be used, and the defined directions may be applicable to the drawings of  FIGS. 2-4 . 
         [0020]    Document feed tray  91  may be supported by housing  6  so as to be pivotable about a rotation axis X that may be located at a rearwardly upward position with respect to housing  6  to extend along a right-left direction. When document feed tray  91  is pivoted about rotation axis X to be opened from a position where document feed tray  91  may cover upper surface  6 A as depicted in  FIG. 1 , document feed tray  91  may be changed to a position where document feed tray  91  may allow a document holding surface  91 A to face upward at a rearward part of housing  6  as depicted in  FIG. 2 . In the illustrative embodiment, the position where document holding surface  91 A may be exposed as depicted in  FIG. 2  may be referred to as a “used position” of document feed tray  91  and the position where document holding surface  91 A may not be exposed as depicted in  FIG. 1  may be referred to as an “unused position” of document feed tray  91 . In the used position, document feed tray  91  may be configured to hold one or more documents that have not been read yet. In the unused position, document feed tray  91  may be configured not to hold any documents because document feed tray  91  may not allow document holding surface  91 A to appear in the unused position. 
         [0021]    Document discharge tray  92  may be disposed at the lower part of housing  6  and may be configured to be inserted into or be drawn from housing  6  along a front-rear direction. As depicted in  FIG. 2 , document discharge tray  92  may be configured to be drawn forward with respect to housing  6 . In the illustrative embodiment, the position where document discharge tray  92  may be drawn forward with respect to housing  6  as depicted in  FIG. 2  may be referred to as a “used position” of document discharge tray  92  and the position where document discharge tray  92  may be accommodated in housing  6  as depicted in  FIG. 1  may be referred to as an “unused position” of document discharge tray  92 . Similar to document feed tray  91 , in the used position, document discharge tray  92  may be configured to hold one or more documents that have been read. In the unused position, document discharge tray  92  may be configured not to hold any documents. 
         [0022]    As depicted in  FIG. 2 , housing  6  may comprise an operating panel  40  that may comprise a keypad  41  and a display unit  42  at upper surface  6 A. Keypad  41  may comprise various buttons (e.g., a start key, a stop key, and numeric keys). Display unit  42  may comprise a liquid crystal display. When document feed tray  91  is located in the unused position, input operations on operating panel  40  by a user may be limited because document feed tray  91  covers operating panel  40  (see  FIG. 1 ). When document feed tray  91  is located in the used position, operating panel  40  may appear to allow all input operations by the user. 
         [0023]      FIGS. 3 and 4  depict an internal configuration of scanner  100 .  FIG. 3  depicts scanner  100  in which both the document feed tray  91  and document discharge tray  92  are located in their unused positions.  FIG. 4  depicts scanner  100  in which document feed tray  91  and document discharge tray  9  are located in their used positions. 
         [0024]    Scanner  100  may comprise a feed roller  62 , a first conveyor roller  63 , image sensors  21 ,  22 , and a second conveyor roller  64  in its inside. In this illustrative embodiment, the reading components, for example, feed roller  62 , first conveyor roller  63 , image sensors  21 ,  22 , and second conveyor roller  64 , used for document reading may be collectively called an image reading unit  20 . Image reading unit  20  may be configured to read a color image or read a monochrome image only. 
         [0025]    One of image sensors  21 ,  22  may be configured to read an image on one side of a document and the other of image sensors  21 ,  22  may be configured to read an image on the other side of the document. In each of image sensors  21 ,  22 , optical elements may be arranged in line along the right-left direction (a direction perpendicular to the drawing surface of  FIG. 4 ). Each of image sensors  21 ,  22  may be configured to convert light reflected from the document into electronic signals and output the electronic signals. For example, a contact image sensor (“CIS”) or a charge-coupled device (“CCD”) may be employed as image sensors  21 ,  22 . 
         [0026]    Scanner  100  may convey one or more documents  9  held on document feed tray  91  along a direction indicated by an arrow D depicted in  FIGS. 2 and 4  from document feed tray  91  to document discharge tray  92 . More specifically, in scanner  100 , document feed tray  91  may be located in the used position for setting one or more documents  9  on document feed tray  91 . As depicted in  FIG. 4 , the user may set one or more documents  9  on document feed tray  91 . The one or more documents  9  held on document feed tray  91  may move toward feed roller  62  by their own weight. Then, feed roller  62  may convey documents  9 , one by one, downstream along a conveying path  61 . Image reading unit  20  may read one or both sides of document  9  that is moving in conveying path  61  when document  9  passes image reading unit  20 . After that, scanner  100  may discharge document  9  onto document discharge tray  92 . That is, document feed tray  91  and document discharge tray  92  may constitute a part of conveying path  61 . 
         [0027]    As depicted in  FIG. 3 , in scanner  100 , when document feed tray  91  is located in the unused position, conveying path  61  may be curved in a substantially U-shape manner at rotation axis X of document feed tray  91 . Therefore, when document feed tray  91  is located in the unused position, scanner  100  may be configured to not perform document reading by image reading unit  20 . 
         [0028]    Scanner  100  may further comprise a control device  10  and a power supply control system  50  in its inside as well as image reading unit  20 . Control device  10  may be configured to control image reading unit  20 . Power supply control system  50  may be configured to control power supplied to each unit or component of scanner  100 . Control device  10  and power supply control system  50  will be described in detail later. 
         [0029]    An electric configuration of scanner  100  is now described. As depicted in  FIG. 5 , scanner  100  may comprise image reading unit  20 , a detector such as sensor  30 , operating panel  40 , power supply control system  50 , control device  10 , a Universal Serial Bus (“USB”) interface (“I/F”)  15  and a network interface (“I/F”)  16 . Sensor  30  may be configured to detect the position of document feed tray  91  in the used position or in the unused position. Power supply control system  50  may be configured to control power supplied to each unit or component of scanner  100 . Control device  10  may be configured to control operations of image reading unit  20 . USB interface  15  and network interface  16  may be communication interfaces for establishing connections between scanner  100  and an output destination device, for example an external device. 
         [0030]    Control device  10  may comprise a central processing unit (“CPU”)  11 , a read-only memory (“ROM”)  12 , a random-access memory (“RAM”)  13 , and a nonvolatile RAM (“NVRAM”)  14 . ROM  12  may store firmware that may control programs for controlling scanner  100  and various settings as well as certain setting values. RAM  13  may be used as a workspace for temporarily storing the control programs read from ROM  12  or as a storage area for temporarily storing image data. 
         [0031]    A reading control device, for example CPU  11 , may control functions of each unit or each component of scanner  100 . CPU  11  may store processing results in RAM  13  or NVRAM  14 , in accordance with the control programs read from ROM  13  and signals sent from sensors. 
         [0032]    USB interface  15  may be configured to allow scanner  100  to communicate with the external device. For example, when an USB memory is connected to USB interface  15 , scanner  100  may output read image data to the USB memory. USB interface  15  may not always be connected with the USB memory but also can be connected with, for example, a personal computer (“PC”). When USB interface  15  is connected with a PC, scanner  100  may be configured to receive various instructions, for example, a scanning instruction or a setting instruction, from the PC via USB interface  15 . 
         [0033]    Similar to USB interface  15 , network interface  16  may be configured to allow scanner  100  to communicate with the external device. Scanner  100  may be configured to output read image data to an external device connected thereto via network interface  16 . Scanner  100  may receive instructions from the external device via network interface  16 . 
         [0034]    The connection between scanner  100  and the external device may be established via other devices as well as USB interface  15  and network interface  16 . For example, when scanner  100  comprises a wireless communication interface, scanner  100  may be connected with the external device via wireless communication. 
         [0035]    Image reading unit  20  may be configured to read an image on a document and output the read image as image data, for example, in PDF format. Image reading unit  20  may be further configured to perform a correction process on the image data as required. Image reading unit  20  may output the image data to, for example, the external device that may be connected with scanner  100  via USB interface  15  or network interface  16 . 
         [0036]    Sensor  30  may be configured to output a signal identifying whether document feed tray  91  is in the used position (an opened state) or in the unused position (a closed state). Sensor  30  may comprise, for example, a light-emitting element and a light-receiving element. When document feed tray  91  is located in the used position, sensor  30  may be configured such that the light-receiving element may receive light from the light-emitting element. When document feed tray  91  is located in the unused position, sensor  30  may be configured such that the light-receiving element may not receive light from the light-emitting element due to an interruption. 
         [0037]    The power supply control performed in scanner  100  is described below. As depicted in  FIG. 6 , scanner  100  may comprise a power source device  51  (an example of a supply device), a switch circuit  52 , and a power supply control device  53 , collectively forming a power supply control system  50 . Switch circuit  52  may be configured to distribute the power supplied from power source device  51  to each unit or each component of scanner  100 . Power supply control device  53  may be configured to control making and breaking of each switch of switch circuit  52 . 
         [0038]    Power source device  51  may comprise a circuit that may be configured to be connected with, for example, a main electricity grid or a battery, and convert the power to an appropriate level to supply to each unit or each component of scanner  100 . Switch circuit  52  may be configured to switch a power supply condition between supplying or not supplying power to each unit or each component of scanner  100  in accordance with a signal outputted from power supply control device  53 . More specifically, scanner  100  may comprise a power source system for image reading unit  20 , a power source system for control device  10 , and a power source system for an external interface (for example, USB interface  15  and network interface  16  in this embodiment). Switch circuit  52  may be configured to switch the power supply condition between supplying or not supplying power to each power source system. Power source device  51  may supply power to sensor  30  and operating panel  40  all the time by bypassing switch circuit  52 . 
         [0039]    A plurality of power-supply modes are now described below. The plurality of power-supply modes may be realized by the switching of the power supply condition by switch circuit  52  between supplying or not supplying power to each power source system. The power-supply modes may include a power saving mode for reducing power consumed by one or more of image reading unit  20  and the other units and components, and a non-power saving mode for not reducing power consumed by image reading unit  20  and the other units and components. 
         [0040]    More specifically, the non-power saving mode may include a ready mode. In the ready mode, scanner  100  may be allowed to perform image reading from a document and data transmission or reception and to receive user operations through operating panel  40 . The power saving mode may include a first power-saving mode and a second power-saving mode. In the first power-saving mode, scanner  100  may be allowed to perform data transmission or reception via USB interface  15 , network interface  16 , or other interfaces and to receive user operations through operating panel  40  but may not be allowed to perform image reading from a document. In the second power-saving mode, scanner  100  may not be allowed to perform image reading from a document and data transmission or reception while operating panel  40 , sensor  30 , and power supply control system  50  may be allowed to operate. 
         [0041]      FIG. 7  depicts a relationship between each mode and a condition of power supply to each unit or each component. In  FIG. 7 , “SUPPLIED” may represent that power is supplied to the unit or the component and “NOT SUPPLIED” may represent that power is not supplied to the unit or the component. As depicted in  FIG. 7 , in the ready mode, power is supplied to all of image reading unit  20 , control device  10 , operating panel  40 , the external interface, and sensor  30 , and scanner  100  may be allowed to perform a scanning operation. Immediately after scanner  100  is up, scanner  100  may operate in the ready mode. When a condition for shifting to the first power-saving mode is met during the ready mode, the mode may be changed to the first power-saving mode. When a condition for shifting to the second power-saving mode is met during the ready mode or during the first power-saving mode, the mode may be changed to the second power-saving mode. 
         [0042]    In the first power-saving mode, switch circuit  52  may interrupt the power supply to image reading unit  20 . That is, switch circuit  52  may interrupt the power supply to image sensors  21 ,  22 , which may consume a larger amount of power, to reduce the power consumption in scanner  100 . However, switch circuit  52  may not interrupt the power supply to control device  10 , operating panel  40 , and the external interface to receive user operations. When a condition for shifting to the ready mode is met, the mode may be changed to the ready mode. 
         [0043]    In the second power-saving mode, switch circuit  20  may interrupt the power supply to control device  10  and the external interface in addition to image reading unit  20 . That is, scanner  100  may not be allowed to perform data transmission or reception to or from the external device. This power supply control may further reduce the power consumption in scanner  100  as compared with the power consumption in scanner  100  in the first power-saving mode. However, switch circuit  20  may not interrupt the power supply to sensor  30 . That is, sensor  30  may be controlled by a circuit different from control device  10 , and thus, sensor  30  may be configured to detect the position of document feed tray  91  in the used position or in the unused position when scanner  100  is in the second power-saving mode. When document feed tray  91  is changed to the used position during the second power-saving mode, scanner  100  may determine that the document feed tray  91  has been changed from the unused position to the used position based on the detection result of sensor  30  and may shift to the ready mode. In the second power-saving mode, operating panel  40  may be supplied with power. That is, operating panel  40  may be controlled by a circuit different from control device  10  and may be configured to receive user operations when scanner  100  is in the second power-saving mode. 
         [0044]    More specifically, power supply control device  53  may store a threshold time period (e.g., a waiting period) that may be a time at which the mode may be changed to the power saving mode. When the elapsed time measured by a timer exceeds the threshold time period since a time period during which the document reading may be performed has elapsed or a user operation (for example, an input through operating panel  40  or an instruction inputted from the external device) has been completed, the mode may be changed to the power saving mode. When document feed tray  91  is located in the used position at the time the elapsed time being measured exceeds the threshold time period, the mode may be changed to the first power-saving mode. When document feed tray  91  is located in the unused position at the time the elapsed time being measured exceeds the threshold time period, the mode may be changed to the second power-saving mode. After the mode is changed to the second power-saving mode, the timer may stop because the power supplied to control device  10  that can control the timer is interrupted. 
         [0045]    Power supply control device  53  may be configured to output, to switch circuit  52 , a signal for supplying or not supplying power to each power source system, in accordance with the current mode. Power supply control device  53  may be directly supplied with power from power source device  51  and configured to work while scanner  100  is in the second power-saving mode. Therefore, power supply control device  53  may control switch circuit  52  by monitoring an output signal from sensor  30  while scanner  100  is in the second power-saving mode. 
         [0046]    A mode switching process for switching among the above-described modes is described with reference to  FIG. 8 . The mode switching process may be performed by power supply control device  53  when power source device  51  is connected to the main electricity grid or the battery and power is supplied to power supply control device  53  from power source device  51 . 
         [0047]    As the mode switching process starts, first, power supply control device  53  may operate in the ready mode in an initial state (step S 101 ). It may be expected that scanner  100  will probably be used immediately after scanner  100  is up. Therefore, the mode may preferably be the ready mode immediately after scanner  100  is up. 
         [0048]    After step S 101 , power supply control device  53  may start the timer to measure time (step S 102 ). The time being measured by the timer may be used for a mode switching determination. The measured time of the timer may be reset to an initial value when document reading is started. The timer may stop measuring time during document reading, and the timer may restart measuring time when the document reading is completed. The measured time of the timer may be reset to the initial value when control device  10  detects a user operation through operating panel  40  or receipt of a signal from the external device. 
         [0049]    Then, power supply control device  53  may determine whether communication is available between scanner  100  and an external device (step S 151 ). The external device may be the USB memory connectable to scanner  100  via USB interface  15  or the PC connectable to scanner  100  via network interface  16 . 
         [0050]    When communication is available between scanner  100  and an external device (step S 151 : YES), power supply control device  53  may specify a time period T 1  (for example, 15 minutes) as the threshold time period for shifting to the power saving mode (step S 152 ). When communication is not available between scanner  100  and an external device (step S 151 : NO), power supply control device  53  may specify a time period T 2  (for example, 3 minutes) as the threshold time period to further reduce the power consumption in scanner  100  (step S 153 ). Time period T 2  may be shorter than time period T 1 . After step S 152  or step S 153 , the routine may move to step S 103 . 
         [0051]    Then, power supply control device  53  may determine whether document feed tray  91  has been changed from the used position to the unused position (step S 103 ). Power supply control device  53  may determine the position of document feed tray  91  based on the output signal sent from sensor  30 . In step S 103 , when sensor  30  detects the position change of document feed tray  91  from the used position to the unused position, power supply control device  53  may make a positive determination (step S 103 : YES). From then on, power supply control device  53  may not make the positive determination in step S 103  until sensor  30  detects again the position change of document feed tray  91  from the used position to the unused position. 
         [0052]    When document feed tray  91  has been changed from the used position to the unused position (step S 103 : YES), power supply control device  53  may determine whether the elapsed time measured by the timer has exceeded the threshold time period (step S 104 ). When the elapsed time measured by the timer has exceeded the threshold time period (step S 104 : YES), power supply control device  53  may perform a second power-saving mode executing process by shifting to the second power-saving mode (step S 105 ). 
         [0053]      FIG. 9  depicts details of the second power-saving mode executing process in step S 105 . In the second power-saving mode executing process, first, power supply control device  53  may change the mode to the second power-saving mode (step S 181 ). In step S 181 , power supply control device  53  may output the signal for supplying or not supplying power to each power source system with respect to switch circuit  52  to control switch circuit  52  for changing the power-supply mode. This may be realized by the switching of the power supply condition by switching switch circuit  52  between supplying and not supplying power to each power source system in the second power-saving mode. That is, when document feed tray  91  is located in the unused position, the user may not be allowed to operate operating panel  40  or to set one or more documents  9  on document feed tray  91 . Therefore, it may be conceivable that the user may not intend to use scanner  100 . Thus, power supply control device  53  may change the mode to the second power-saving mode for more effectively reducing the power consumption in scanner  100 . 
         [0054]    Then, power supply control device  53  may determine whether document feed tray  91  has been changed from the unused position to the used position based on the output signal from sensor  30  (step S 182 ). While document feed tray  91  is located in the unused position (step S 182 : NO), the routine may wait until document feed tray  91  is changed from the unused position to the used position. 
         [0055]    When document feed tray  91  has been changed to the used position (step S 182 : YES), power supply control device  53  may change the mode to the ready mode (step S 183 ). In step S 183 , power supply control device  53  may output the signal for supplying or not supplying power to each power source system with respect to switch circuit  52  to control switch circuit  52  for changing the power-supply mode. This may be realized by the switching of the power supply condition by switch circuit  52  between supplying and not supplying power to each power source system in the ready mode, because it may be conceivable that the user will use scanner  100 . Then, power supply control device  53  may reset the measured time of the timer to the initial value and restart the timer to measure time (step S 184 ). After step S 184 , power supply control device  53  may exit the second power-saving mode executing process. 
         [0056]    Back to the mode switching process of  FIG. 8 , after performing the second power-saving mode executing process in step S 105 , the routine may move to step S 151 . 
         [0057]    When the elapsed time measured by the timer has not exceeded the threshold time period (step S 104 : NO), power supply control device  53  may determine whether scanner  100  is currently performing document reading (step S 131 ). The measured time of the timer may be reset when document reading is started and the timer may stop measuring time during document reading. Therefore, the elapsed time measured by the timer does not exceed the threshold time period when scanner  100  is currently performing document reading. Thus, the case where the elapsed time measured by the timer has not exceeded the threshold time period may include a case where scanner  100  is currently performing document reading and a case where the elapsed time has not exceeded the threshold time period since the document reading was completed. 
         [0058]    When scanner  100  is currently performing document reading (step S 131 : YES), power supply control device  53  may cancel the reading of one or more documents following the current target document after a time period during which the current target document is read is over (step S 132 ). That is, when scanner  100  stops the current document reading in the middle of reading the current target document, scanner  100  may not obtain completely-read image data. Even when scanner  100  restarts the reading of the current target document, the quality of an image may be degraded due to variations in the reading speed. Accordingly, scanner  100  may continue the reading of the document being currently read to complete the reading of the current target document. However, scanner  100  may not perform reading of any documents following the current target document because a problem may arise during the conveyance of the following documents. After the completion of step S 132 , the current document reading is completed. Therefore, power supply control device  53  may restart the timer, which has stopped, to measure time. After step S 132  or when scanner  100  is not currently performing the document reading (step S 131 : NO), the routine may move to step S 151 . 
         [0059]    Back to step S 103 , when document feed tray  91  has not been changed from the used position to the unused position (step S 103 : NO), power supply control device  53  may determine whether document feed tray  91  has been changed from the unused position to the used position (step S 111 ). In step S 111 , when sensor  30  detects the position change of document feed tray  91  from the unused position to the used position, power supply control device  53  may make a positive determination (step S 111 : YES). From then on, power supply control device  53  may not make the positive determination until sensor  30  detects the position change of document feed tray  91  from the unused position to the used position. 
         [0060]    When document feed tray  91  has been changed from the unused position to the used position (step S 111 : YES), power supply control device  53  may change to the ready mode (step S 112 ). In step S 112 , power supply control device  53  may output the signal for supplying or not supplying power to each power source system with respect to switch circuit  52  to control switch circuit  52  for changing the power-supply mode. This may be realized by switching the power supply condition by switch circuit  52  between supplying and not supplying power to each power source system in the ready mode. That is, power supply control device  53  may control switch circuit  52  to supply power to each unit or each component of scanner  100  and thus scanner  100  may be allowed to perform document reading. When scanner  100  is in the ready mode at the time of the position change of document feed tray  91  from the unused position to the used position, power supply control device  53  may not need to perform step S 112 . After step S 112 , power supply control device  53  may reset the measured time of the timer to the initial value and restart the timer to measure time (step S 113 ). After step S 113 , the routine may move to step S 151 . 
         [0061]    When document feed tray  91  has not been changed from the unused position to the used position (step S 111 : NO), power supply control device  53  may perform a power saving mode switching process for determining whether an automatic mode change to the first or second power-saving mode is performed (step S 121 ). 
         [0062]      FIG. 10  depicts details of the power saving mode switching process in step S 121 . In the power saving mode switching process, first, power supply control device  53  may determine whether the elapsed time measured by the timer has exceeded the threshold time period (step S 201 ). When the elapsed time measured by the timer has exceeded the threshold time period (step S 201 : YES), power supply control device  53  may determine whether document feed tray  91  is located in the used position (step S 202 ). 
         [0063]    When document feed tray  91  is located in the used position (step S 202 : YES), power supply control device  53  may change the mode to the first power-saving mode (step S 203 ). In step S 203 , power supply control device  53  may output the signal for supplying or not supplying power to each power source system with respect to switch circuit  52  to control switch circuit  52  for changing the power-supply mode. This may be realized by switching the power supply condition by switch circuit  52  between supplying and not supplying power to each power source system in the first power-saving mode. In the first power-saving mode, power supply control system  50  may control switch circuit  52  to stop supplying power to image reading unit  20  while continuing to supply power to operating panel  40 , the external interface, and control device  10  that may control operating panel  40  and the external interface. Therefore, in the first power-saving mode, scanner  100  may be allowed to receive an input through operating panel  40  or an input from the external device. When scanner  100  has already been in the first power-saving mode at the time of step S 203 , power supply control device  53  may not need to perform step S 203 . 
         [0064]    When document feed tray  91  is located in the unused position (step S 202 : NO), power supply control device  53  may perform the second power-saving mode executing process (step S 221 ). In the second power-saving mode, power supply control system  50  may control switch circuit  52  to stop supplying power to image reading unit  20 , the external interface, and control device  10  that may control operating panel  40  and the external interface. Therefore, in the second power-saving mode, scanner  100  may not be allowed to receive an input from the external device. The processing of step S 221  may be the same as the processing of step S 105 . After completing step S 221 , power supply control device  53  may exit the power saving mode switching process. 
         [0065]    After step S 203  or when the elapsed time measured by the timer has not exceeded the threshold time period (step S 201 : NO), power supply control device  53  may determine whether scanner  100  has received a user operation (step S 204 ). The user operation to scanner  100  may be, for example, an input operation on operating panel  40 , an issue of a scanning instruction from the PC, or an access to data from the PC. When scanner  100  has not received a user operation (step S 204 : NO), power supply control device  53  may exit the power saving mode switching process. 
         [0066]    When scanner  100  has received a user operation (step S 204 : YES), power supply control device  53  may change the mode to the ready mode (step S 205 ). In step S 205 , power supply control device  53  may output the signal for supplying or not supplying power to each power source system with respect to switch circuit  52  to control switch circuit  52  for changing the power-supply mode. This may be realized by the switching of the power supply condition by switch circuit  52  between supplying and not supplying power to each power source system in the ready mode for performing processing corresponding to the user operation. That is, power supply control system  50  may control switch circuit  52  to supply power to each unit or each component of scanner  100  and this scanner  100  may be allowed to perform document reading. When scanner  100  has already been in the ready mode at the time of step S 205 , power supply control device  53  may not need to perform step S 205 . After step S 205 , power supply control device  53  may reset the measured time of the timer to the initial value and restart the timer to measure time (step S 206 ). After step S 206 , power supply control device  53  may exit the power saving mode switching process. 
         [0067]    Back to the mode switching process of  FIG. 8 , after performing the power saving mode switching process of step S 121 , the routine may move to step S 151 . 
         [0068]    As described above, in scanner  100  according to the illustrative embodiment, while scanner  100  does not perform reading of a document  9 , the user convenience may be ensured by the mode change to the power saving mode (in particular, the second power-saving mode in this illustrative embodiment) performed in accordance with the position change of document feed tray  91  from the used position to the unused position document  9 . When document feed tray  91  is changed from the used position to the unused position during document reading, the mode may not be changed to the first power-saving mode or the second power-saving mode while at least reading of the current target document is performed. By doing so, the currently-performed reading may be completed and thus the degradation in the image quality may be reduced. Accordingly, scanner  100  according to the illustrative embodiment may achieve image-reading quality and the user convenience. 
         [0069]    While various aspects of the disclosure has been described in detail with reference to the specific illustrative embodiments thereof, it would be apparent to those skilled in the art that various changes, arrangements and modifications may be applied therein without departing from the spirit and scope of the invention. For example, the image-reading device may not be limited to the scanner but may be applied to any devices having a reading function, for example, multifunction peripheral devices or facsimile machines. 
         [0070]    In the above-described illustrative embodiment, the mode may be changed to the first or second power-saving mode on condition that document feed tray  91  is located in the used position or in the unused position, respectively. The condition may not be limited to the specific illustrative embodiment. In other illustrative embodiments, for example, the mode may be changed to the first or second power-saving mode on condition that document discharge tray  92  is located in the used position or in the unused position, respectively. That is, in the above-described illustrative embodiment, the power supply may be controlled in accordance with the position (the used position or the unused position) of document feed tray  91 . Nevertheless, in other illustrative embodiments, for example, the power supply may be controlled in accordance with the position (the user position or the unused position) of document discharge tray  92 . 
         [0071]    In the above-described illustrative embodiment, there may be three modes, for example, the ready mode, the first power-saving mode, and the second power-saving mode. Nevertheless, in other illustrative embodiments, for example, the mode may be changed between two modes, for example, the ready mode and the second power-saving mode (or the first power-saving mode). There may be other modes (for example, a third power-saving mode in which power supply control system  50  may control switch circuit  52  to stop supplying power to the external interface while continuing the power supply to control device  10  for a duration of the mode shifting from the first power-saving mode to the second power-saving mode). 
         [0072]    In the above-described illustrative embodiment, power source device  51  may supply power to operating panel  40  at all times. Nevertheless, in other illustrative embodiments, for example, power supply control system  50  may control switch circuit  52  to stop supplying power to operating panel  40  in the second power-saving mode. 
         [0073]    In the above-described illustrative embodiment, when document feed tray  91  is located in the unused position (step S 103 : YES), power supply control device  53  may change the mode to the second power-saving mode after the elapsed time measured by the timer exceeds the threshold time period (step S 104 : YES). However, it may be unnecessary to wait at all times until the elapsed time measured by the timer exceeds the threshold time period. In other illustrative embodiments, for example, power supply control device  53  may change the mode to the second power-saving mode immediately after document feed tray  91  is changed from the used position to the unused position (or immediately after document reading is completed when scanner  100  is performing the document reading). The immediate mode change to the second power-saving mode after the position change of document feed tray  91  from the used position to the unused position may achieve further power savings. 
         [0074]    In the above-described illustrative embodiment, power supply control device  53  may change the threshold time period based on whether communication is available between scanner  100  and an external device. Nevertheless, in other illustrative embodiments, for example, the threshold time period may not change. 
         [0075]    In the above-described illustrative embodiment, when document feed tray  91  is changed from the used position to the unused position, scanner  100  may continue the reading of the document being read. Nevertheless, in other illustrative embodiments, for example, scanner  100  may be configured to perform reading of all of the following documents placed on document feed tray  91  when document feed tray  91  is changed to the unused position. However, the following documents may be damaged because it may be difficult to convey the documents from document feed tray  91  that may be located in the unused position. Accordingly, it may be preferable to complete the reading of the current target document only and not to perform reading of the following documents. 
         [0076]    In the above-described illustrative embodiment, the threshold time period for shifting to the first power-saving mode and the threshold time period for shifting to the second power-saving mode may be commonly used. Nevertheless, in other illustrative embodiments, for example, these threshold time periods may be individually specified. In this case, for example, the threshold time periods may be individually specified based on whether communication is available between scanner  100  and an external device. 
         [0077]    In the above-described illustrative embodiment, when scanner  100  is in the first power-saving mode, power supply control device  53  may control switch circuit  52  to stop supplying power to image reading unit  20  to reduce the power consumption in scanner  100 . Nevertheless, in other illustrative embodiments, for example, power supply control device  53  may decrease the power supplied to image reading unit  20  to reduce the power consumption in scanner  100 , instead of stopping the power supply. In the above-described illustrative embodiment, when scanner  100  is in the second power-saving mode, power supply control device  53  may control switch circuit  52  to stop supplying power to control device  10  and the external interface in addition to image reading unit  20 . Similarly, power supply control device  53  may decrease the power supplied to at least one of image reading unit  20 , control device  10 , and the external interface to reduce the power consumption in scanner  100 . 
         [0078]    While the disclosure has included various example structures and illustrative embodiments, it will be understood by those skilled in the art that other variations and modifications of the structures and embodiments described above may be made without departing from the scope of the disclosure. Other structures and embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the embodiments disclosed herein. It is intended that the specification and the described examples are illustrative.