Patent Publication Number: US-RE49536-E

Title: Image reading apparatus with multi-sheet feed detection

Description:
This application is a reissue application of U.S. Pat. No. 10,015,338, which was filed as U.S. patent application Ser. No. 15/334,361 on Oct. 26, 2016 and issued on Jul. 3, 2018, which claims priority to Japanese Patent Application No. 2015-213924 filed on Oct. 30, 2015, the disclosure of which are incorporated herein by reference in its entirety.  
     BACKGROUND 
     1. Technical Field 
     The present invention relates to an image reading apparatus such as a scanner that reads images of original documents. 
     2. Related Art 
     Typical image reading apparatuses separate a plurality of original documents mounted on an original platen (placement section) one by one, transport the original documents, and read images of the original documents (see, for example, JP-A-2012-41118). 
     Such image reading apparatuses include a multi-sheet feed detection sensor (multi-sheet feed detection section) for detecting whether a plurality of original documents are transported in an overlapped state (hereinafter, also referred to as a multi-sheet feed). Such image reading apparatuses have a separation mode for separating the original documents on the original platen and transporting the original documents, and a non-separation mode for manually feeding the original documents. While the non-separation mode is selected, the multi-sheet feed state detected by the multi-sheet feed detection sensor is disabled. 
     In other words, in the image reading apparatuses, original documents such as envelopes and center-folded original documents, which are transported one by one but may be erroneously detected as a multi-sheet feed, are manually fed one by one in the non-separation mode. 
     In some cases, however, image reading apparatuses have to read a plurality of original documents including original documents such as envelopes that tend to be erroneously detected as a multi-sheet feed, even if a single envelope is fed, and original documents that are rarely detected as an error such as paper. In such a case, it is laborious to feed the original documents one by one to read the original documents in the non-separation mode. On the other hand, if the original documents are read in the separation mode, the multi-sheet feed detection sensor may erroneously detect an error, and the reading operation may be stopped. In such a case, the erroneously detected original documents are to be read in the non-separation mode, and this operation causes the read data to be split into a plurality of files corresponding to before and after the detected error. 
     SUMMARY 
     An advantage of some aspects of the invention is that there is provided an image reading apparatus capable of reducing the splitting of read data into a plurality of files when original documents to be read include original documents that tend to be erroneously detected as a multi-sheet feed. 
     Hereinafter, an apparatus for solving the above-mentioned problem and its operational advantages will be described. An image reading apparatus that can solve the above-mentioned problem includes a transport section configured to transport original documents along a transport path, a reading section configured to read images of the original documents transported by the transport section, an output controller configured to output data of the original documents read by the reading section, a multi-sheet feed detection section configured to detect a multi-sheet feed of the original documents transported by the transport section, and an instruction section configured to issue an instruction to disable multi-sheet feed detection by the multi-sheet feed detection section. After a job for sequentially transporting a plurality of original documents to perform a reading operation to read images is interrupted by multi-sheet feed detection performed by the multi-sheet feed detection section, and if the job is restarted in a disabling mode in which the multi-sheet detection is disabled in accordance with an instruction from the instruction section, the output controller outputs, as a data stream that can be saved as a single file, first data that is read in the reading operation before the interruption and second data that is read in the reading operation after the restart. 
     With this structure, the output controller outputs the first data and the second data as a data stream. Accordingly, the first data read before the interruption and the second data read after the restart can be merged into a single file even if the job is interrupted by the multi-sheet feed detection. Consequently, the splitting of the read data into a plurality of files can be reduced when the original documents to be read include original documents that tend to be erroneously detected as a multi-sheet feed. 
     It is preferable that the image reading apparatus further include a transport detection section configured to detect the original documents transported by the transport section. The disabling mode includes an original document unit disabling mode for disabling the multi-sheet feed detection by the multi-sheet feed detection section until the trailing edges of the original documents pass through the multi-sheet feed detection section, and if the original document unit disabling mode is instructed by the instruction section, in response to detection of the passage of the trailing edges of the original documents through the multi-sheet feed detection section based on a detection signal by the transport detection section, the multi-sheet feed detection by the multi-sheet feed detection section is enabled. 
     With this structure, for example, to read the original documents that tend to be erroneously detected as a multi-sheet feed, the original document unit disabling mode can be selected to disable the multi-sheet feed detection by the multi-sheet feed detection section until the original documents have passed through the multi-sheet feed detection section. After the passage of the original documents, the multi-sheet feed detection can be enabled. 
     It is preferable that in the image reading apparatus, the disabling mode include a job unit disabling mode for disabling the multi-sheet feed detection by the multi-sheet feed detection section until the job is complete. If the job unit disabling mode is instructed by the instruction section, in response to the job completion, the multi-sheet feed detection by the multi-sheet feed detection section is enabled. 
     With this structure, in the job unit disabling mode, the multi-sheet feed detection can be disabled until the job is complete. Accordingly, the job interruption caused by erroneous detection can be reduced, for example, when original documents that tend to be erroneously detected as a multi-sheet feed are included in the original documents to be read in a single job. After job completion, the multi-sheet feed detection can be enabled. 
     It is preferable that the image reading apparatus further include a placement section on which the original documents to be read are mounted, a placement detection section configured to detect the original documents mounted on the placement section, and a transport detection section configured to detect the original documents mounted on the placement section and transported by the transport section. From the job interruption to the job restart, the disabling mode set in accordance with the instruction from the instruction section is maintained regardless of the detection results of the placement detection section and the transport detection section. 
     With this structure, from the job interruption to the job restart, the placement detection section and the transport detection section detect resetting of the original documents. However, from the job interruption to the job restart, regardless of the detection results of the placement detection section and the transport detection section, the disabling mode is maintained, and thereby the job can be restarted in the disabling mode after resetting the original documents. 
     It is preferable that in the image reading apparatus, the disabling mode include a disable maintaining mode for maintaining the state in which the multi-sheet feed detection by the multi-sheet feed detection section is disabled until the power supply is switched off. With this configuration, in the disable maintaining mode, in response to a disable instruction by the instruction section, the multi-sheet feed detection can be disabled until the power is switched off. Accordingly, the job interruption caused by erroneous detection can be reduced when performing a plurality of jobs including original documents that tend to be erroneously detected as a multi-sheet feed. 
     It is preferable that, in the image reading apparatus, the instruction section issue an instruction for starting the job, and the interrupted job be restarted in accordance with the start instruction from the instruction section. 
     With this configuration, the interrupted job can be restarted at any time by instructing the instruction section to issue an instruction to start the job. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG.  1    is a perspective view of an image reading apparatus according to an embodiment. 
         FIG.  2    is a schematic side cross-sectional view of the image reading apparatus. 
         FIG.  3    is a schematic plan view of a transport surface section of a body section. 
         FIG.  4    is a schematic side view of overlapped original documents detected by a multi-sheet feed sensor. 
         FIG.  5    is a block diagram illustrating an electrical configuration and a functional configuration of the image reading apparatus. 
         FIG.  6    is a flowchart illustrating multi-sheet feed detection disabling processing. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, an image reading apparatus according to an embodiment will be described with reference to the attached drawings. As illustrated in  FIG.  1   , an image reading apparatus  11  according to the embodiment includes an apparatus body  12  (hereinafter, simply referred to as “body  12 ”) that has a substantially trapezoidal shape in side view, and an original support  13  that is an example placement section having a mounting surface  13 A onto which original documents D (see  FIG.  2   ) that are to be read are mounted (set). The original documents D mounted on the original support  13  are fed one by one to a feed port  12 A that is open to an upper portion of the body  12 . The fed original documents D are transported in the body  12  along a predetermined transport path  32  (see  FIG.  2   ), and the images of the original documents are read at a reading position on the transport path. The original documents are then discharged from a discharge port  12 B that is open to a front lower portion of the body  12  and stacked, for example, on a discharge tray  18 A (see  FIG.  2   ). 
     The original support  13  includes a first support section  14  that is rotatably connected to the body  12  at a base end portion (lower end portion), and a second support section  15  that is rotatably connected to an end portion of the first support section  14  at a base end portion. A slidable auxiliary support section  16  is provided at an end portion of the second support section  15 . The original support  13  extends upward in an inclined manner from the rear of the body  12  and can be arranged in an open position (use position) where the original support  13  serves as a support on which the original documents D can be mounted, as illustrated in  FIG.  1   , or in a closed position (stored position) where the original support  13  can be adjusted by a user to cover an upper surface portion and a front surface portion  12 C of the body  12  by turning the original support  13  from the open position toward the paper surface in  FIG.  1   . 
     A pair of edge guides  17  that can be slid in width directions X which intersect (specifically, are orthogonal to) a transport direction Y in which the original documents D are transported are provided on the mounting surface  13 A of the original support  13 . The original documents D mounted on the mounting surface  13 A are held by the pair of edge guides  17 , and thereby the original documents D are positioned in the width direction X with respect to the feed port  12 A. Note that the width direction X is a main scanning direction along which the image reading apparatus  11  reads images of the original documents D, and the transport direction Y is a sub-scanning direction. 
     As illustrated in  FIG.  1    and  FIG.  2   , the body  12  includes a body section  18  and a cover section  19  that is connected to the body section  18  such that the cover section  19  can rotate about a front end portion of the body section  18 . A transport path  32  from the feed port  12 A to the discharge port  12 B is provided between the body section  18  and the cover section  19  as illustrated in  FIG.  2    when the cover section  19  is arranged in the closed position illustrated in  FIG.  1    and  FIG.  2   . A transport surface section  39  (see  FIG.  3   ) that is a surface section of the transport path  32  is exposed when a user operates the operation section  19 A illustrated in  FIG.  1    to release the engagement of the cover section  19  and rotates the cover section  19  from the closed position illustrated in  FIG.  1    toward the paper surface illustrated in  FIG.  1    and to the open position. By opening the cover section  19  and exposing the transport surface section  39 , the user can, for example, remove lodged (jammed) original documents D and perform maintenance of rollers  33 A to  36 A for feeding and transporting original documents (see  FIG.  2   ). 
     An instruction section  20  for issuing an instruction for starting a job, an instruction for disabling multi-sheet feed detection, or the like is provided on the front surface portion  12 C of the body  12  (cover section  19 ), as illustrated in  FIG.  1   . The term “multi-sheet feed” refers to a state in which a plurality of original documents D mounted on the original support  13  are transported in an overlapped state. The instruction section  20  includes a plurality of switches  21  to  26  for issuing instructions to the image reading apparatus  11 . Specifically, the instruction section  20  includes various switches such as a power switch  21 , a start switch  22 , a stop switch  23 , a read mode selection switch  24 , a multi-sheet feed detection disabling switch  25  (multi-sheet feed detection skip switch), and a wireless communication switch  26 . 
     The power switch  21  is operated by a user to issue an instruction for switching between starting power supply to the image reading apparatus  11  and stopping the power supply. The start switch  22  is used to issue an instruction to start a job for transporting at least one, for example, a plurality of original documents D mounted on the original support  13  in sequence and performing a reading operation for reading images. The stop switch  23  is used to issue a stop instruction for interrupting or stopping the job started by the operation of the start switch  22 . The read mode selection switch  24  is used to issue an instruction for specifying an image reading mode for reading images in a reading operation, for example, a color mode (e.g., monochrome or color) or image quality. 
     The multi-sheet feed detection disabling switch  25  is operated by a user to issue an instruction for disabling multi-sheet feed detection to switch to a disabling mode for disabling multi-sheet feed detection for detecting whether a multi-sheet feed has occurred. The wireless communication switch  26  is used to issue an instruction for switching wireless communication on and off. 
     At a position adjoining to the instruction section  20 , a notification section  27  that includes pilot lamps that can light up and/or blink and go out, for example, light-emitting diodes (LEDs), or pilot lamps that can change colors when lit, is provided. The notification section  27  is used to notify a user of, for example, whether the power supply is turned on or off, a currently selected mode, or whether multi-sheet feed detection is enabled or disabled by turning on or off the pilot lamps or by changing their colors. 
     An image reading processing mechanism  30  for image reading processing (scan processing) is provided in the body  12  of the image reading apparatus  11 , as illustrated in  FIG.  2   . The image reading processing mechanism  30  includes a transport section  31  that transports the original documents D. The transport section  31  guides and transports a plurality of original documents D mounted on the original support  13  one by one from the feed port  12 A along a plate-like feed guide  32 A into the body  12  and transports the fed original documents D along the transport path  32  at a constant transport speed. 
     The transport section  31  includes a feeding roller pair  33  that is disposed at an upstream end position of the transport path  32  in the body  12 , and a feeding roller pair  34  that is disposed downstream of the feeding roller pair  33  in the transport direction. The transport section  31  further includes a transport roller pair  35  that is disposed upstream of the reading position of the original documents D and a transport roller pair  36  that is disposed downstream of the reading position in the transport direction Y. 
     The feeding roller pairs  33  and  34  include driving rollers  33 A and  34 A and driven rollers  33 B and  34 B. The transport roller pairs  35  and  36  include driving rollers  35 A and  36 A and driven rollers  35 B and  36 B. The driven rollers  33 B to  36 B rotate in response to the rotation of corresponding driving rollers  33 A to  36 A respectively. 
     The driving rollers  33 A to  36 A of the roller pairs  33  to  36  are rotated and driven by the power of a transporting motor  37  that is the power source of the rollers. The driven rollers  34 B of the feeding roller pair  34  serve as retard rollers, and the coefficients of friction against the original documents D on their outer circumferential surfaces are larger than those of the driving rollers  34 A. Accordingly, the feeding roller pair  34  serves as a separation mechanism  38  that separates the original documents D one by one and sends the separated original documents to the downstream side in the transport direction Y. That is, a plurality of original documents D mounted on the original support  13  are fed, for example, from the lowest original in sequence one by one from the feed port  12 A into the body  12  by the rotation of the feeding roller pair  33  and are further separated one by one and fed to the downstream side in the transport direction Y by the rotation of the feeding roller pair  34 . 
     As illustrated in  2 , a reading section  40  that reads images of the original documents D transported by the transport section  31  is provided at the reading position in the middle of the transport path  32  that is defined by the feeding roller pairs  33  and  34  and the transport roller pairs  35  and  36  in the body  12 . The reading section  40  includes a first reading section  40 A and a second reading section  40 B that are disposed on both sides of the transport path  32  at positions slightly shifted in the transport direction Y such that the sections  40 A and  40 B do not directly face each other. The pair of reading sections  40  includes a light source  41  that can emit light toward the original document D being transported and an image sensor  42  that extends in the main scanning direction (width direction X). In a normal reading mode for reading one side (front surface) of the original document D, the first reading section  40 A performs a reading operation, and in a two-sided reading mode for reading both sides (front and rear surfaces) of the original document D, the first reading section  40 A and the second reading section  40 B perform a reading operation together. 
     The light source  41  may be, for example, an LED or a fluorescent lamp. The image sensor  42  receives the light emitted from the light source  41  and reflected by the original documents D, or the like, converts the received light into electrical signals, and outputs pixel signals of values corresponding to the amounts of received light. The image sensor  42  may be, for example, a linear image sensor. The image reading apparatus  11  can perform color scanning and monochrome scanning (gray-scale scanning). The color scanning includes a method in which light sources of RGB emit light in a time-series order and pixel signals of RGB are acquired from a monochrome image sensor in this order, and a method in which an image sensor that includes photoelectric converters covered with respective RGB color filters is provided, a white light source emits light, and pixel signals of RGB are acquired from the photoelectric converters. Any one of the color scanning methods may be employed. In the description below, the light source  41  and the image sensor  42  may be referred to as components of the first reading section  40 A, a first light source  41 A, and a first image sensor  42 A, respectively and as components of the second reading section  40 B, a second light source  41 B, and the second image sensor  42 B, respectively. 
     A color reference plate  43  is disposed on the opposite side of the transport path  32  to the image sensor  42 . The color reference plate  43  is used to obtain a white reference value for shading correction, and a white reference plate or gray reference plate is used. The gray reference plate is used to detect the position and area of the original document D from data read by using the color reference plate  43  as a background (gray background) of the original, based on a difference between the colors or luminance values of the original and the background. It is preferable that the white reference plate be used as the color reference plate  43  when detecting an original by using a sensor dedicated for original detection. 
     The image sensor  42  may be, for example, a contact type image sensor that has a plurality of photoelectric converters aligned in the main scanning direction (width direction X). More specifically, the image sensor  42  may be a complementary metal oxide semiconductor (CMOS). The image sensor  42  performs photoelectric conversion of the light received by each photoelectric converter and outputs pixel signals corresponding to the amounts of received light. 
     A controller  50  provided in the body  12  controls the transporting motor  37 , the light source  41  and the image sensor  42  included in the reading section  40  ( 40 A and  40 B). The controller  50  further controls the image reading apparatus  11  in accordance with instructions given by operation signals from the instruction section  20  operated by a user. 
     The transport surface section  39  that is a surface section of a lower side of the transport path  32  for the original documents D is described with reference to  FIG.  3   . The transport surface section  39  that is defined by an upper surface of the body section  18  includes a transport plate  18 B that covers the upper surface of the body section  18  and a plurality of ribs  18 C that protrude from the upper surface and extend in parallel with each other along the transport direction Y. In a substantially central portion of the transport surface section  39  in the width direction X, the driving rollers  33 A and  34 A included in the feeding roller pairs  33  and  34 , and the driving rollers  35 A and  36 A included in the transport roller pairs  35  and  36  are disposed respectively as pairs with a certain space in the width direction X in this order from the upstream side in the transport direction Y. A placement sensor  45 , which is an example placement detection section for detecting the original documents D mounted on the original support  13 , is disposed between the pair of driving rollers  33 A included in the feeding roller pair  33 . The placement sensor  45  is, for example, a contact sensor having a lever, and detects whether the original documents D mounted on the original support  13  exist in response to a pressing operation of the lever. 
     A multi-sheet feed sensor  46 , which is an example multi-sheet feed detection section for detecting a multi-sheet feed of the original documents D transported by the transport section  31 , is disposed between the feeding roller pair  34  and the transport roller pair  35  in the transport direction Y, as illustrated in  FIG.  3    and  FIG.  4   . The multi-sheet feed sensor  46  is, for example, an ultrasonic sensor, and includes a transmitter  46 A (see  FIG.  4   ) that can transmit ultrasound and a receiver  46 B that is disposed on the opposite side of the transport path  32  from the transmitter  46 A and can receive the ultrasound from the transmitter  46 A. The multi-sheet feed sensor  46  detects a multi-sheet feed of the original documents D using the principle that ultrasound from the transmitter  46 A is attenuated due to spaces between overlapped two original documents. The degree of attenuation of the ultrasound passed through two or more original documents D is larger than that of the ultrasound passed through one original document D. Accordingly, if a detected value exceeds (is below) a predetermined threshold value due to the large degree of attenuation, it is determined to be a multi-sheet feed. In contrast, since the degree of attenuation of the ultrasound passed through one original document D is small, the detected value does not exceed the predetermined threshold value, and it is not determined to be a multi-sheet feed. 
     Accordingly, if the original document D that has an overlapped portion, for example, an envelope or folded paper is used, since the degree of attenuation of the ultrasound due to the spaces in the overlapped portion is large, the multi-sheet feed sensor  46  may erroneously determine the one original document D being transported to be a multi-sheet feed. Accordingly, to read the original document D that tends to be erroneously determined to be a multi-sheet feed, the user can operate the multi-sheet feed detection disabling switch  25  to issue an instruction for disabling the multi-sheet feed detection by the multi-sheet feed sensor  46  to set a disabling mode that disables the multi-sheet feed detection. 
     Furthermore, a transport sensor  47 , which is an example transport detection section for detecting the original documents D mounted on the original support  13  and transported by the transport section  31 , is disposed between the pair of driving rollers  35 A included in the transport roller pair  35 . The transport sensor  47  is, for example, a contact sensor having a lever (contactor), and detects the leading edge when the leading edge of the original document D pushes the lever and a non-detection state (off) is switched to a detection state (on), and detects the trailing edge when the trailing edge passes through the lever and the lever is not pushed and the detection state is switched to the non-detection state. The detection result of the transport sensor  47  is used to control the time of starting and ending the reading operation of the reading section  40  ( 40 A, and  40 B) that is disposed downstream in the transport direction Y. 
     With reference to  FIG.  5   , an electrical configuration of the image reading apparatus  11  is described. As illustrated in  FIG.  5   , the controller  50  includes a computer  51  that has a microprocessor, and the like, and a storage section  52 . The controller  50  further includes an input section  55  that has an input interface for inputting various kinds of data and signals from a host device  53 , and an output section  56  that has an output interface for outputting data read by the image reading apparatus  11  to the host device  53 . 
     The controller  50  further includes a timing generator (TG)  57  for outputting pulse signals defining the time of various operations including an operation of reading a pixel signal for the reading section  40  (image sensors  42 A and  42 B). The controller  50  also includes an analog front end (AFE)  58  that performs analog-to-digital conversion (A/D conversion) of pixel signals input from the image sensors  42 A and  42 B. The storage section  52  includes, for example, a nonvolatile memory and a random access memory (RAM). 
     The image reading apparatus  11  is connected to the host device  53  via a communication cable. The host device  53  may be, for example, a personal computer (PC). It should be noted that the host device  53  is not limited to the PC, and may be a personal digital assistant (PDA), a tablet PC, or a smart device such as a smart phone. The host device  53  includes a creation section  60  that creates a file based on data output from the image reading apparatus  11 . 
     The storage section  52  in  FIG.  5    stores a program (PR) and the like that includes a program for multi-sheet feed detection disabling processing illustrated in the flowchart in  FIG.  6   . The computer  51  in  FIG.  5    serves as a functional section of various functions illustrated in  FIG.  5    by executing the program PR. That is, as illustrated in  FIG.  5   , the computer  51  includes, as the functional section, a main controller  62 , a transport controller  63  for controlling the transporting motor  37 , a mode controller  64 , a reading controller  65  for controlling the reading section  40 , and an output controller  66  for controlling output of data of the original documents D read by the reading section  40 . 
     The transport controller  63  drives the transporting motor  37  in accordance with an instruction from the main controller  62  to rotate the roller pairs  33  to  36  such that the original documents D mounted on the original support  13  is fed into the body  12  one by one. The transport controller  63  further transports the fed original documents D along the transport path  32  at a constant transport speed corresponding to the read conditions. 
     The mode controller  64  switches an enabling mode for enabling the multi-sheet feed detection by the multi-sheet feed sensor  46  and a disabling mode for disabling the multi-sheet feed detection in accordance with an instruction from the multi-sheet feed detection disabling switch  25 . The disabling mode according to the embodiment includes an original document unit disabling mode, a job unit disabling mode, and a disable maintaining mode, which control different time periods for maintaining a disabled state, respectively. These disabling modes are set, for example, depending on an operation of the multi-sheet feed detection disabling switch  25 . 
     In the original document unit disabling mode, multi-sheet feed detection by the multi-sheet feed sensor  46  is disabled until the trailing edges of the original documents D pass through the multi-sheet feed sensor  46 . The original document unit disabling mode is set when a user performs a first operation (for example, presses the multi-sheet feed detection disabling switch  25  once) and a first instruction is issued. 
     In the job unit disabling mode, the multi-sheet feed detection by the multi-sheet feed sensor  46  is disabled until the job ends. The job unit disabling mode is set when a user performs a second operation (for example, presses the multi-sheet feed detection disabling switch  25  twice) and a second instruction is issued. 
     In the disable maintaining mode, the multi-sheet feed detection by the multi-sheet feed sensor  46  is disabled until the power supply is switched off. The disable maintaining mode is set when a user performs a third operation (for example, presses long the multi-sheet feed disabling switch  25 ) and a first instruction is issued. 
     The enabling mode is set when any of the first to third operations is not performed or a reset operation (for example, the stop switch  23  is pressed once while a reading operation is interrupted) is performed. 
     The reading controller  65  controls the reading section  40  while the original documents D are being transported to read images of the original documents D. Specifically, the reading controller  65  outputs pulse signals to the image sensor  42  via the TG  64  to control reading time for reading pixel signals and thereby the reading operations are controlled. The analog pixel signals output from the reading section  40  are converted into digital pixel signals via the AFE  58  and input into the output controller  66  as read data. 
     The output controller  66  performs known image correction processing such as shading correction and gamma correction to the read data containing the input digital pixel signals to generate image data of the original documents D. Then, the output controller  66  outputs the generated image data to the host device  53  via the output section  56 . 
     Hereinafter, the multi-sheet feed detection disabling processing to be executed by the computer  51  is described with reference to the flowchart in  FIG.  6   . The computer  51  starts a job for performing a reading operation of the original documents D and performs multi-sheet feed detection disabling processing in response to an operation of the start switch  22  while the original documents D are mounted on the original support  13 . In this embodiment, a single job includes transporting the original documents D mounted on the original support  13  one by one from the first original, causing the reading section  40  to read images, and reading an image on the last original document D. 
     In step S 11 , the computer  51  initializes the value of N corresponding to the pages of the original documents D to one. In step S 12 , the computer  51  performs an operation for reading an Nth original document D. Specifically, the transport controller  63  drives the transporting motor  37  to feed and transport the original documents D mounted on the original support  13 , and the reading controller  65  instructs the reading section  40  to read images of the original documents D at the time the original documents D pass through the reading position. 
     In step S 13 , the computer  51  determines whether the enabling mode for enabling the multi-sheet feed detection has been set. If the enabling mode has been set (step S 13 : YES), in step S 14 , the computer  51  determines whether a multi-sheet feed has occurred. For example, when the original documents D are envelopes, the multi-sheet feed sensor  46  may be turned on while the envelopes are transported one by one, and the multi-sheet feed sensor  46  may erroneously determine that a multi-sheet feed has occurred (step S 14 : YES). 
     In step S 15 , the computer  51  interrupts the reading operation. Specifically, the transport controller  63  stops the driving of the transporting motor  37 , and the reading controller  65  stops the reading of the images of the original documents D by the reading section  40 . Furthermore, in step S 16 , the computer  51  turns on an interruption flag, and in step S 17 , outputs first data. Specifically, the output controller  66  outputs the image data of the original documents D (Nth to first original documents) read before the job interruption as the first data. 
     In step S 18 , the computer  51  notifies the user of the detection of a multi-sheet feed. In step S 19 , the computer  51  determines whether the disabling mode for disabling the multi-sheet feed detection has been set. While the disabling mode has not been set (step S 19 : NO), the computer  51  stands by until the disabling mode is set. In response to an operation of the multi-sheet feed detection disabling switch  25  by the user, the mode controller  64  sets the disabling mode corresponding to the instruction. If the disabling mode has been set (step S 19 : YES), in step S 20 , the computer  51  determines whether a restart instruction has been issued. Specifically, while the start switch  22  is not pressed by the user (step S 20 : NO), the computer  51  stands by until the start switch  22  is pressed. If the start switch  22  is pressed, the computer  51  moves to the processing in step S 12 , and restarts the interrupted reading operation of the Nth original document D. 
     In step S 13 , if the disabling mode has been set (step S 13 : NO), the computer  51  moves to the processing in step S 21 . In step S 14 , if the multi-sheet feed sensor  46  has not detected a multi-sheet feed (off) (step S 14 : NO), the computer  51  moves to the processing in step S 21 . 
     In step S 21 , the computer  51  determines whether the transport sensor  47  is switched from on to off. That is, the transport sensor  47  is switched from off to on when the leading edge of the original document D is transported to the transport sensor  47 . While the original documents D are passing through the transport sensor  47  (step S 21 : NO), the computer  51  moves the processing to step S 12 . If the trailing edge of the original document D passes through the transport sensor  47  and the transport sensor  47  is switched from on to off (step S 21 : YES), in step S 22 , the computer  51  determines whether the original document unit disabling mode has been set. 
     If the original document unit disabling mode has been set (step S 22 : YES), in step S 23 , the mode controller  64  changes the original document unit disabling mode to the enabling mode. If the mode that has been set is not the original document unit disabling mode (step S 22 : NO), in step S 24 , while the mode is maintained, the computer  51  determines whether the placement sensor  45  is off. 
     Specifically, if the original documents D are mounted on the original support  13  and the placement sensor  45  is on (step S 24 : NO), in step S 25 , the computer  51  adds one to N, and moves to step S 12  to perform the reading operation of the next original document D. 
     If all of the original documents D that have been mounted on the original support  13  are fed and the placement sensor  45  is off (step S 24 : YES), in step S 26 , the computer  51  determines whether the interruption flag is on. 
     If the interruption flag is on (step S 26 : YES), in step S 27 , the computer  51  outputs the second data. That is, the output controller  66  outputs the image data read in the reading operation performed after the interruption as the second data that can be merged with the first data output in step S 17  into a single file as a data stream. In step S 28 , the computer  51  turns off the interruption flag. 
     In step S 26 , if the interruption flag is off (step S 26 : NO), in step S 29 , the computer  51  outputs the image data. That is, since the job is not interrupted, the output controller  66  outputs the image data of all original documents D from the original document read first to the original document read last. 
     In step S 30 , the computer  51  determines whether the job unit disabling mode has been set. If the job unit disabling mode has been set (step S 30 : YES), in step S 31 , the mode controller  64  changes the job unit disabling mode to the enabling mode, and ends the processing. If the job unit disabling mode has not been set (stop S 30 : NO), the mode controller  64  maintains the settings, and ends the processing. 
     Now, the operation of reading targets including original documents D that tend to be erroneously detected as a multi-sheet feed such as envelopes and folded paper will be described. It is assumed that, for example, three original documents D have been mounted on the original support  13 , and in a single job, an operation for reading all (three) original documents D mounted on the original support  13  is performed. 
     When the power of the image reading apparatus  11  is turned on and the start switch  22  is pressed, in the enabling mode that enables the multi-sheet feed detection, the computer  51  feeds and transports the original documents D and instructs the reading section  40  to read the original documents D. 
     Then, for example, if the second original document D is an envelope, the multi-sheet feed sensor  46  detects a multi-sheet feed, and interrupts the job. That is, the computer  51  completes the reading operation of the first original document D, stops the transport of the second original document D, and outputs the first data that is the data of the first original document D read in the reading operation performed before the interruption. Then, the computer  51  displays a message that prompts the user to reset the second and subsequent original documents D onto the original support  13 , and a message that prompts the user to set the multi-sheet feed detection mode on a display section (not illustrated) of the image reading apparatus  11  or the host device  53 , or notifies the content by voice, or the like. 
     From the job interruption to the job restart, the disabling mode that is set in accordance with an instruction from the instruction section  20  is maintained regardless of the detection results from the placement sensor  45  and the transport sensor  47 . The interrupted job is restarted in accordance with a start instruction from the instruction section  20 . 
     After the disabling mode is set and the start switch  22  is pressed, the computer  51  restarts the job in the disabling mode in which the multi-sheet feed detection is disabled according to the instruction from the instruction section  20 , and performs the operation for reading the second and subsequent original documents D, which have been reset. That is, the interrupted job is restarted in accordance with the start instruction from the instruction section  20 . Then, the original document D that was erroneously detected as a multi-sheet feed before the interruption is transported and read in the state the multi-sheet feed detection is disabled. 
     While the original document unit disabling mode is set in accordance with an instruction from the instruction section  20 , if the computer  51  detects that the trailing edge of the second original document D has passed through the multi-sheet feed sensor  46  based on a detection signal from the transport sensor  47 , the computer  51  enables the multi-sheet feed detection by the multi-sheet feed sensor  46 . That is, since the transport sensor  47  is disposed downstream of the multi-sheet feed sensor  46  in the transport direction Y, the original document D has already passed through the multi-sheet feed sensor  46  when the original document D passes through the transport sensor  47 . Accordingly, the computer  51  switches to the enabling mode when the transport sensor  47  is switched from on to off. When the job unit disabling mode or the disable maintaining mode has been set, the set mode is maintained. 
     While the job unit disabling mode is set in accordance with an instruction by the instruction section  20 , when the last (for example, the third) original document D has passed through the transport sensor  47  and the job is complete, the mode controller  64  enables the multi-sheet feed detection by the multi-sheet feed sensor  46 . Then, the output controller  66  outputs the second data of the second and third original documents D read in the reading operation performed after the restart as data that can be merged with the first data into a single file as a data stream. If the disable maintaining mode has been set, the computer  51  maintains the disabling mode until the power is switched off. 
     The host device  53  that has acquired the first data output from the image reading apparatus  11  stands by until the second data is output. The second data is output from the image reading apparatus  11 , and then, in the host device  53 , the creation section  60  merges the first data and the second data into a single 
     According to the above-described embodiment, the following advantages can be achieved. 
     1. Time output controller  66  outputs the first data and the second data as a data stream. Accordingly, the first data read before the interruption, and the second data read after the restart, can be merged into a single file even if the job is interrupted by the multi-sheet feed detection. Accordingly, the splitting of the read data into a plurality of files can be reduced when the original documents D to be read include the original documents D that tend to be erroneously detected as a multi-sheet feed. 
     2. For example, to read the original documents D that tend to be erroneously detected as a multi-sheet feed, the original document unit disabling mode can be selected to disable the multi-sheet feed detection by the multi-sheet feed sensor  46  until the original documents D have passed through the multi-sheet feed sensor  46 . After the passage of the original documents D, the multi-sheet feed detection can be enabled. 
     3. In the job unit disabling mode, the multi-sheet feed detection can be disabled until the job is complete. Accordingly, the job interruption due to erroneous detection can be reduced, for example, when the original documents D that tend to be erroneously detected as a multi-sheet feed are included in the original documents D to be read in a single job. After the job is complete, the multi-sheet feed detection can be enabled. 
     4. From the job interruption to the job restart, when the original documents D are reset, the placement sensor  45  and the transport sensor  47  detect the resetting of the original documents D. However, from the job interruption to the job restart, regardless of the detection results of the placement sensor  45  and the transport sensor  47 , the disabling mode is maintained, and thereby the job can be restarted in the disabling mode after resetting of the original documents D. 
     5. In the disable maintaining mode, in response to a disable instruction from the instruction section  20 , the multi-sheet feed detection is disabled until the power is switched off. Accordingly, the job interruption caused by erroneous detection can be reduced when performing a plurality of jobs including original documents D that tend to be erroneously detected as a multi-sheet feed. 
     6. The interrupted job can be restarted at any time by instructing the instruction section  20  to issue an instruction to start the job. The above-described embodiment can be modified as described below. 
     In the above embodiment, the placement sensor  45  and the transport sensor  47  may be non-contact sensors, for example, photoelectronic sensors. In the above-described embodiment, the multi-sheet feed sensor  46  may be a sensor that detects a multi-sheet feed based on the thickness of the original documents B. 
     In the above-described embodiment, the output controller  66  may output the first data and the second data after the job is complete. In the above-described embodiment, the creation section  60  may be provided in the image reading apparatus  11 . That is, for example, the output controller  66  may output the first data and the second data to the creation section provided in the image reading apparatus  11 , and the output section  56  may output the file created by the creation section to the host device  53 . 
     In the above-described embodiment, when the job is interrupted, the reading operation may be restarted by transporting the original documents D that have been erroneously detected as a multi-sheet feed as it is without resetting the original documents D onto the original support  13 . 
     In the above-described embodiment, the next original document D may be transported before the reading operation of the preceding original document D is complete. In the above-described embodiment, the pattern of the notification section  27  may be changed for the individual mode selected from the disabling modes. For example, the notification section  27  may light one of LEDs of different colors corresponding to the original document unit disabling mode, the job unit disabling mode, and the disable maintaining mode, respectively. 
     In the above-described embodiment, the start switch  22  for issuing a job start instruction may be omitted from the instruction section  20 . For example, the computer  51  may start the job in accordance with a start instruction input from the host device  53 . Furthermore, the computer  51  may restart the interrupted job in response to an instruction of the disabling mode from the multi-sheet feed detection disabling switch  25 . 
     In the above-described embodiment, in a case where the disable maintaining mode is set, the disabling mode may be switched to the enabling mode and then the power of the image reading apparatus  11  may be switched off in turning off (shutting off the power supply) the power in accordance with an instruction from the power switch  21 . Furthermore, in turning on the power of the image reading apparatus  11 , the disabling mode may be switched to the enabling mode. Furthermore, the disable maintaining mode may be continued after the power is turned off and further the power is turned on. 
     In the above-described embodiment, the disabling mode and the enabling mode may be switched in accordance with an instruction from the instruction section  20 . For example, the computer  51  may set the disabling mode when the multi-sheet feed detection disabling switch  25  is pressed once, and set the enabling mode when the multi-sheet feed detection disabling switch  25  is pressed again. That is, it is not always necessary that the disabling mode includes the original document unit disabling mode, the job unit disabling mode, and the disable maintaining mode. The disabling mode may include at least one of the original document unit disabling mode, the job unit disabling mode, and the disable maintaining mode. 
     In the above-described embodiment, the original support  13  and the placement sensor  45  may be omitted. For example, a user may insert the original documents D into the feed port  12 A. Furthermore, a job may be ended after the number of original documents D to be read in the job is input via the instruction section  20  or the host device  53 , and the reading operation of the original documents D of the specified number is complete. Furthermore, a job end may be instructed from the instruction section  20  (for example, by pressing the stop switch  23 , or the like by the user). 
     In the above-described embodiment, while the job is interrupted, the multi-sheet feed detection modes may be changed in accordance with the detection results of the placement sensor  45  and the transport sensor  47 . For example, based on the detection results of the placement sensor  45  and the transport sensor  47 , whether the original documents D, which have been detected as a multi-sheet feed, are reset onto the original support  13  can be determined. Consequently, for example, after the multi-sheet feed sensor  46  detects a multi-sheet feed and the job is interrupted, if the job is restarted without resetting the original documents D onto the original support  13 , the enabling mode may be changed to the disabling mode (for example, the original document unit disabling mode) and then the reading operation may be performed. 
     In the above-described embodiment, the transport sensor  47  may be omitted. For example, passage of the trailing edges of the original documents D through the multi-sheet feed sensor  46  may be detected based on the number of the original documents D fed and transported, or the read image data. 
     In the above-described embodiment, the instruction section  20  may be a touch panel. Furthermore, the multi-sheet feed detection disabling switch  25  is not limited to the push switch, and alternatively, a lever switch, a slide switch, or a mode switch may be employed. 
     The original documents may be any kind of original documents as long as they can be fed and transported by the transport section  31 , for example, single sheets of paper, envelopes, cards, business cards, receipts, credit cards, insurance policies, or the like. The image reading apparatus is not limited to the sheet-feed type image reading apparatus, and alternatively, may be a flat-bed type image reading apparatus having an automatic document feeding function (automatic document feeder) as an example transport section. 
     The entire disclosure of Japanese Patent Application No. 2015-213924, filed Oct. 30, 2015 is expressly incorporated by reference herein.