Image reading device and image reading method for image reading device

Abstract

To provide an image reading device and an image reading method for an image reading device that can improve convenience for a user.SOLUTION: An image reading device comprises: a DC motor; a roller that is driven by the DC motor; a reading unit that can read an image from a document conveyed by the roller; and a control unit that can control the drive of the DC motor. The control unit can detect the power load value of the DC motor. When the control unit determines that the power load value of the DC motor has exceeded a first threshold while controlling the DC motor to convey the document at a first conveyance speed, it can control the DC motor to convey the document at a second conveyance speed slower than the first conveyance speed.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an image reading apparatus that reads an image from a document and an image reading method of the image reading apparatus.

Background Art

[0002] For example, Patent Document 1 discloses an image reading apparatus that conveys a document by driving a DC motor and reads an image from the conveyed document. In such an image reading apparatus, the timing when the image reading apparatus becomes unusable is determined based on the rotation speed of the DC motor. In particular, when the timing when the image reading apparatus becomes unusable suddenly arrives and the period during which the image reading apparatus cannot be used becomes long, the convenience of the user is impaired. Therefore, in order to minimize the period during which the image reading apparatus cannot be used, a margin is set for the timing when the image reading apparatus becomes unusable.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the image reading apparatus described in Patent Document 1, although the timing when the image reading apparatus becomes unusable can be specified early, the timing itself when the image reading apparatus becomes unusable is not extended, and it is desired to improve the convenience of the user.

Means for Solving the Problems

[0005] An image reading device that solves the above problems comprises a DC motor, rollers driven by the DC motor, a reading unit capable of reading an image from a document transported by the rollers, and a control unit capable of controlling the drive of the DC motor, wherein the control unit is capable of detecting the power load value of the DC motor, and after the control unit has controlled the DC motor to transport a document at a first transport speed and has determined that the power load value of the DC motor has exceeded a first threshold, it is possible to control the DC motor to transport the document at a second transport speed that is slower than the first transport speed.

[0006] An image reading method for an image reading device that solves the above problems is an image reading method for an image reading device comprising a DC motor, rollers driven by the DC motor, a reading unit capable of reading an image from a document transported by the rollers, and a control unit capable of controlling the drive of the DC motor, wherein the control unit can control the DC motor to transport the document at a second transport speed slower than the first transport speed after determining that the power load value of the DC motor exceeds a first threshold when controlling the DC motor to transport the document at a first transport speed. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic side cross-sectional view showing an image reading device. [Figure 2] This is a block diagram showing the electrical configuration of an image reading device. [Figure 3] This is a schematic diagram showing the threshold values ​​for the power load of the second drive unit. [Figure 4] This is a flowchart showing the power load detection process. [Figure 5] This is a flowchart showing the power load determination process. [Figure 6] This is a schematic diagram showing the threshold values ​​for the power load of the second drive unit. [Figure 7] This is a flowchart showing the power load determination process. [Figure 8] This is a flowchart showing the power load detection process. [Figure 9] This is a flowchart showing the power load detection process. [Modes for carrying out the invention]

[0008] [First Embodiment] Hereinafter, an embodiment of an image reading device and an image reading method for the image reading device will be described with reference to the drawings. In the following description, the direction in which the document is transported will be referred to as the transport direction Y, and the direction intersecting the transport direction Y will be referred to as the width direction X.

[0009] <Configuration of the image reading device 10> As shown in Figure 1, the image reading device 10 is configured to read an image from the original document D. In particular, the image reading device 10 is configured to transport the original document D and to read an image from the transported original document D.

[0010] The image reading device 10 includes a housing 11. The housing 11 is configured to house various components. The housing 11 comprises a main body 12 and a cover 13. The cover 13 is connected to the main body 12 in a manner that allows it to be opened and closed.

[0011] The housing 11 is equipped with a feed port 11A. The feed port 11A is provided between the main body 12 and the cover 13. The feed port 11A is an opening for feeding the original document D into the housing 11 before scanning.

[0012] The housing 11 is equipped with an output port 11B. The output port 11B is provided between the main body 12 and the cover 13. The output port 11B is an opening for discharging the scanned document D from the housing 11 to the outside.

[0013] The housing 11 is equipped with a transport path 14. The transport path 14 is provided between the main body 12 and the cover 13. The transport path 14 is provided between the feed port 11A and the discharge port 11B. The transport path 14 is a path for transporting the document D from the feed port 11A to the discharge port 11B.

[0014] The image reading device 10 may include a document support 15. The document support 15 is provided above the paper feed port 11A. The document support 15 is configured to extend from the housing 11. The document support 15 can hold one or more documents D before reading.

[0015] The image reading device 10 includes a paper feed guide 16. The paper feed guide 16 is housed in the housing 11. The paper feed guide 16 is provided below the paper feed port 11A. The paper feed guide 16 guides the document D fed from the paper feed port 11A into the housing 11 along the conveyance path 14.

[0016] The image reading device 10 may include a stacker 17. The stacker 17 is provided below the discharge port 11B. The stacker 17 may be housed in the housing 11 in a slidable state in the front-rear direction intersecting the width direction X.

[0017] <Conveying unit 20> The image reading device 10 includes a conveying unit 20. The conveying unit 20 is housed in the housing 11. The conveying unit 20 is configured to convey the document D along the conveyance path 14. The conveying unit 20 is configured to convey the document D to the reading area SA and discharge it from the discharge port 11B.

[0018] The conveying unit 20 includes a paper feed roller 21. The paper feed roller 21 is provided at the upstream end of the conveyance path 14. The paper feed roller 21 is provided at a position facing the paper feed guide 16. The paper feed roller 21 rotates by the driving force transmitted from a first driving unit 25 described later. That is, the paper feed roller 21 is configured to be driven by the first driving unit 25 described later. The paper feed roller 21 is configured to feed the document D placed on the document support 15 one by one from the paper feed port 11A into the housing 11. The paper feed roller 21 feeds the document D along the paper feed guide 16.

[0019] The transport unit 20 includes a pair of feed rollers 22. The feed roller pair 22 is located downstream of the paper feed roller 21 in the transport direction Y. The feed roller pair 22 includes a feed drive roller 22A and a feed separation roller 22B. The feed drive roller 22A and the feed separation roller 22B are located on either side of the transport path 14. The feed drive roller 22A rotates due to a driving force transmitted from a first drive unit 25, which will be described later. In other words, the feed drive roller 22A is configured to be driven by the first drive unit 25, which will be described later. The feed separation roller 22B rotates due to a driving force transmitted from a second drive unit 26, which will be described later. In other words, the feed separation roller 22B is configured to be driven by the second drive unit 26, which will be described later.

[0020] The transport unit 20 includes a transport roller pair 23. The transport roller pair 23 is located downstream of the feed roller pair 22 in the transport direction Y. The transport roller pair 23 is located upstream of the reading area SA in the transport direction Y. The transport roller pair 23 transports the original document D before reading to the reading area SA.

[0021] The transport roller pair 23 comprises a transport drive roller 23A and a transport driven roller 23B. The transport drive roller 23A and the transport driven roller 23B are positioned so as to straddle the transport path 14. The transport drive roller 23A rotates due to a driving force transmitted from a second drive unit 26, which will be described later. In other words, the transport drive roller 23A is configured to be driven by the second drive unit 26, which will be described later. The transport driven roller 23B rotates together with the rotation of the transport drive roller 23A.

[0022] The transport unit 20 includes a pair of discharge rollers 24. The discharge rollers 24 are located downstream of the transport rollers 23 in the transport direction Y. The discharge rollers 24 are located downstream of the reading area SA in the transport direction Y. The discharge rollers 24 discharge the scanned document D to the outside of the housing 11. The discharge rollers 24 are configured to transport the document D during scanning together with the transport rollers 23.

[0023] The discharge roller pair 24 comprises a discharge drive roller 24A and a discharge driven roller 24B. The discharge drive roller 24A and the discharge driven roller 24B are positioned so as to straddle the conveying path 14. The discharge drive roller 24A rotates due to a driving force transmitted from a second drive unit 26, which will be described later. In other words, the discharge drive roller 24A is configured to be driven by the second drive unit 26, which will be described later. The discharge driven roller 24B rotates together with the rotation of the discharge drive roller 24A.

[0024] The transport unit 20 includes a first drive unit 25. The first drive unit 25 is the drive source for the paper feed roller 21 and the feed drive roller 22A. The first drive unit 25 rotates the paper feed roller 21 and the feed drive roller 22A. The first drive unit 25 may be, for example, a DC motor.

[0025] The transport unit 20 includes a second drive unit 26. The second drive unit 26 is the drive source for the feed / feed separation roller 22B, the transport drive roller 23A, and the discharge drive roller 24A. The second drive unit 26 rotates the feed / feed separation roller 22B, the transport drive roller 23A, and the discharge drive roller 24A. The second drive unit 26 may be, for example, a DC motor. In other words, the image reading device 10 is equipped with a DC motor.

[0026] The image reading device 10 includes a position detection unit 27. The position detection unit 27 may be capable of detecting the rotational position of the transport drive roller 23A, or it may be capable of detecting the rotational position of either the feed / feed separation roller 22B or the discharge drive roller 24A. The position detection unit 27 may be, for example, an encoder.

[0027] The image reading device 10 may include one or more detection units that perform detection related to image reading. In particular, the image reading device 10 may include one or more detection units that perform detection related to the original document D.

[0028] Specifically, the image reading device 10 includes a first document detection unit 28. The first document detection unit 28 is located upstream of the paper feed roller 21 in the transport direction Y. The first document detection unit 28 is capable of detecting the presence or absence of a document D placed on the document support 15. The first document detection unit 28 may be a contact-type sensor having, for example, a lever, or a non-contact sensor such as an optical sensor.

[0029] The image reading device 10 includes a second document detection unit 29. The second document detection unit 29 is provided along the transport path 14. The second document detection unit 29 is provided downstream of the feed roller pair 22 in the transport direction Y. The second document detection unit 29 is provided upstream of the transport roller pair 23 in the transport direction Y. The second document detection unit 29 is capable of detecting the carrier sheet that holds the document D. The second document detection unit 29 is also capable of detecting the presence or absence of the document D in the transport path 14. The second document detection unit 29 may be a contact-type sensor having, for example, a lever, or it may be a non-contact sensor such as an optical sensor.

[0030] The image reading device 10 includes a third document detection unit 30. The third document detection unit 30 is provided along the transport path 14. The third document detection unit 30 is provided downstream of the transport roller pair 23 in the transport direction Y. The third document detection unit 30 is provided upstream of the reading area SA in the transport direction Y. The third document detection unit 30 is capable of detecting the presence or absence of a document D. In particular, the third document detection unit 30 is also capable of detecting the presence or absence of a document D in the transport path 14. The third document detection unit 30 may be a contact-type sensor having, for example, a lever, or it may be a non-contact sensor such as an optical sensor.

[0031] <Reading section 31> The image reading device 10 includes a reading unit 31. The reading unit 31 is housed in the housing 11. The reading unit 31 is located downstream of the transport roller pair 23 in the transport direction Y. The reading unit 31 is located upstream of the discharge roller pair 24 in the transport direction Y. The reading unit 31 is configured to read images from the original document D being transported along the transport path 14. In other words, the reading unit 31 can read images from the original document D being transported by various rollers.

[0032] The reading unit 31 may include a first reading unit 31A and a second reading unit 31B. The first reading unit 31A and the second reading unit 31B are arranged so as to straddle the transport path 14. The first reading unit 31A and the second reading unit 31B are positioned slightly offset from each other in the transport direction Y. The first reading unit 31A is configured to read an image from the front surface of the document D. The second reading unit 31B is configured to read an image from the back surface of the document D.

[0033] The first reading unit 31A includes a first light source 32A. The first light source 32A is capable of irradiating light into the reading area SA. The first light source 32A is capable of irradiating light into the document D being transported in the reading area SA. The first light source 32A may be composed of, for example, an LED or a fluorescent lamp.

[0034] The first reading unit 31A includes a first image sensor 33A. The first image sensor 33A is capable of reading an image from a document D being transported in the reading area SA. The first image sensor 33A converts the received light into photoelectric energy. The first image sensor 33A outputs an output signal with a value corresponding to the amount of light received. The first image sensor 33A may be a contact-type image sensor. The first image sensor 33A may be a CMOS image sensor.

[0035] The first image sensor 33A may be a monochrome sensor or a color sensor. The first reading unit 31A may be configured to read the document D in full color. The first reading unit 31A may be configured to read the document D using three RGB colors. The first reading unit 31A may be configured to read the document D in grayscale.

[0036] The first reading unit 31A includes a first background plate 34A. The first background plate 34A is positioned opposite the second light source 32B and the second image sensor 33B, which will be described later. The first background plate 34A reflects the light emitted from the second light source 32B and causes it to enter the second image sensor 33B. The first background plate 34A is read together with the document D by the second image sensor 33B. The first background plate 34A is read as a background together with the document D by the second image sensor 33B. The first background plate 34A may be white or gray.

[0037] The second reading unit 31B has the same function as the first reading unit 31A. Therefore, a detailed explanation of the second reading unit 31B is omitted. The second reading unit 31B comprises a second light source 32B, a second image sensor 33B, and a second background plate 34B. The second light source 32B has the same function as the first light source 32A. The second image sensor 33B has the same function as the first image sensor 33A. The second background plate 34B has the same function as the first background plate 34A.

[0038] Hereafter, the first light source 32A and the second light source 32B may be collectively referred to as light source 32. The first image sensor 33A and the second image sensor 33B may be collectively referred to as image sensor 33. The first background plate 34A and the second background plate 34B may be collectively referred to as background plate 34.

[0039] <Control Unit 40> The image reading device 10 includes a control unit 40. The control unit 40 comprehensively controls the image reading device 10 and may control various operations performed by the image reading device 10. In other words, the control unit 40 performs control related to image reading. The control unit 40 may include one or more processors that execute various processes according to a program, one or more dedicated hardware circuits such as application-specific integrated circuits that execute at least some of the various processes, or a combination thereof. The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to execute processing. Memory, or computer-readable media, includes any readable media that can be accessed by a general-purpose or dedicated computer.

[0040] <Electrical configuration of image reading device 10> Now, with reference to Figure 2, the electrical configuration of the image reading device 10 will be explained. As shown in Figure 2, the image reading device 10 includes an operating unit 18. The operating unit 18 can be operated by the user from outside the housing 11. The operating unit 18 may include at least one of a power switch, a start switch, a stop switch, and a setting switch.

[0041] The image reading device 10 includes a notification unit 19. The notification unit 19 is capable of notifying predetermined information. The notification unit 19 may include at least one of the following: a display unit for displaying images, an audio output unit for outputting sound, and a light-emitting unit for emitting light. The operation unit 18 and the notification unit 19 may be provided as separate components, or they may be provided as an integrated unit, such as a touch panel.

[0042] The control unit 40 is connected to the operation unit 18, notification unit 19, first drive unit 25, second drive unit 26, position detection unit 27, first document detection unit 28, second document detection unit 29, third document detection unit 30, and reading unit 31. The control unit 40 can receive signals from the operation unit 18, position detection unit 27, first document detection unit 28, second document detection unit 29, third document detection unit 30, and reading unit 31. The control unit 40 can output signals to the notification unit 19, first drive unit 25, second drive unit 26, and reading unit 31.

[0043] In particular, the control unit 40 controls the reading unit 31 to read an image from the document D based on the input of a reading instruction. Specifically, the control unit 40 can control the drive of the first drive unit 25. The control unit 40 can control the drive of the second drive unit 26. The control unit 40 controls the reading unit 31 to read an image from the document D being transported by the transport unit 20.

[0044] The control unit 40 comprises various functional units that operate by executing a program. Specifically, the control unit 40 includes a main control unit 41, a transport control unit 42, a reading control unit 43, and an image processing unit 44. The main control unit 41 comprehensively controls the image reading device 10.

[0045] The transport control unit 42 controls the transport of the document D along the transport path 14. The transport control unit 42 drives the first drive unit 25 and the second drive unit 26 according to the instructions of the main control unit 41.

[0046] In particular, the transport control unit 42 may drive and control the first drive unit 25 and the second drive unit 26 to transport the document D at a transport speed corresponding to the reading resolution. To give a specific example, when the reading resolution is relatively low at 300 dpi, the transport control unit 42 transports the document D at a higher speed than when the reading resolution is relatively high at 600 dpi.

[0047] The reading control unit 43 controls the reading unit 31 via a timing generator 45, which will be described later. In particular, the reading control unit 43 controls the emission of light from the light source 32. The reading control unit 43 controls the image sensor 33 to perform a reading operation. As a result, the reading control unit 43 controls the reading unit 31 to read the image of the document D.

[0048] The image processing unit 44 processes the image data of the image read by the reading unit 31. In particular, the image processing unit 44 can correct the image data based on the results of the analysis of the read image data. The image processing unit 44 outputs the corrected image data to the terminal device 100.

[0049] The control unit 40 includes a timing generator 45. In the figure, the timing generator 45 is indicated as TG. The timing generator 45 outputs a pulse signal indicating the reading operation timing to the reading unit 31. The control unit 40 also includes an analog front end 46. In the figure, the analog front end 46 is indicated as AFE. The analog front end 46 converts the pixel signals from the image sensor 33 from analog signals to digital signals.

[0050] The image reading device 10 is connected to the terminal device 100 in a communication manner. The image reading device 10 may be connected to the terminal device 100 by a wired connection or by a wireless connection. The terminal device 100 may be, for example, a personal computer or a mobile terminal device.

[0051] The terminal device 100 includes a terminal control unit 101. The terminal control unit 101 comprehensively controls the terminal device 100 and may control various operations performed by the terminal device 100. The terminal device 100 is communicably connected to an image reading device 10 that performs control related to image reading. In other words, the terminal control unit 101 also performs control related to image reading.

[0052] The terminal device 100 includes a terminal operation unit 102 and a terminal display unit 103. The terminal operation unit 102 is operable by the user; that is, the terminal operation unit 102 can receive user instructions. The terminal display unit 103 is configured to display images.

[0053] <Drive control by control unit 40> Here, we will explain the drive control by the control unit 40. In particular, we will mainly explain the drive control of the second drive unit 26, but the drive control of the second drive unit 26 can be performed in the same manner.

[0054] The control unit 40 is configured to control the second drive unit 26 by feedback control based on speed control data. The speed control data is data that defines the speed profile. The speed profile is data that defines the target rotational speed of the second drive unit 26. The speed control data is stored in the memory of the control unit 40.

[0055] Specifically, the control unit 40 acquires the actual rotational speed of the second drive unit 26 based on the signal reception interval from the position detection unit 27. Based on the speed control data, the control unit 40 acquires a target rotational speed corresponding to the rotational position of the second drive unit 26.

[0056] The control unit 40 calculates a command value to bring the actual rotational speed corresponding to the rotational position of the second drive unit 26 closer to the target rotational speed. The command value may be, for example, a PWM command value. The control unit 40 outputs a current corresponding to the calculated command value as a drive signal to the second drive unit 26. As a result, the control unit 40 drives the second drive unit 26 by the drive amount corresponding to the command value. In this way, the control unit 40 can control the second drive unit 26 according to the speed profile based on the speed control data.

[0057] The control unit 40 acquires the power load value of the second drive unit 26. More specifically, the control unit 40 acquires the power load value based on the current value output to the second drive unit 26. In particular, the control unit 40 may acquire the power load value based on the duty cycle of the current output to the second drive unit 26 in accordance with the PWM command value. The control unit 40 may acquire the power load value based on the PWM command value. The power load value decreases as the actual rotational speed of the second drive unit 26 approaches the target rotational speed, and increases as the actual rotational speed of the second drive unit 26 moves away from the target rotational speed. In this way, the control unit 40 can detect the power load value of the second drive unit 26.

[0058] <Threshold for power load capacity> Now, referring to Figure 3, the relationship between the rotational speed of the second drive unit 26 and the power load value of the second drive unit 26 will be explained.

[0059] As shown in Figure 3, Graph 50 is a graph in which the rotational speed of the second drive unit 26 is assigned to the vertical axis and the power load value of the second drive unit 26 is assigned to the horizontal axis. Graph 50 shows the first threshold TH1. Graph 50 shows the second threshold TH2.

[0060] The first threshold TH1 is a threshold used to determine whether an abnormality may occur in the drive of the second drive unit 26 at the current rotational speed, but whether an abnormality may not occur in the drive of the second drive unit 26 at a rotational speed lower than the current rotational speed. The first threshold TH1 is a threshold value for the power load of the second drive unit 26 relative to the rotational speed of the second drive unit 26. The power load value of the second drive unit 26 is set to correspond to the rotational speed of the second drive unit 26. In particular, the first threshold TH1 is inversely proportional to the rotational speed of the second drive unit 26. That is, the slower the rotational speed of the second drive unit 26, the larger the first threshold TH1 becomes.

[0061] To give a specific example, when the rotational speed of the second drive unit 26 is speed v11, the first threshold TH1 becomes value Tr11 as the power load value of the second drive unit 26. When the rotational speed of the second drive unit 26 is slower than speed v11, speed v12, the first threshold TH1 becomes value Tr12 as the power load value of the second drive unit 26. Value Tr12 is greater than value Tr11. When the rotational speed of the second drive unit 26 is slower than speed v12, speed v13, the first threshold TH1 becomes value Tr13 as the power load value of the second drive unit 26. Value Tr13 is greater than value Tr12.

[0062] The second threshold TH2 is a threshold used to determine if there is a possibility of an abnormality occurring in the drive of the second drive unit 26. In particular, unlike the first threshold TH1, the second threshold TH2 is also a threshold used to determine if there is a possibility of an abnormality occurring in the drive of the second drive unit 26 even when the rotational speed is reduced. The second threshold TH2 is an absolute threshold for the power load value of the second drive unit 26. The second threshold TH2 is judged with higher priority than the first threshold TH1. The second threshold TH2 is a predetermined constant value Tr2 as the power load value of the second drive unit 26, regardless of the rotational speed of the second drive unit 26. Furthermore, the second threshold TH2 is a value greater than the first threshold TH1. The intersection of the first threshold TH1 and the second threshold TH2 is the speed v2.

[0063] <Power load detection process> Now, with reference to Figure 4, the power load detection process will be explained. The power load detection process is a process executed by the control unit 40 at predetermined intervals. Here, the order of each process can be arbitrarily rearranged as long as it does not deviate from the purpose of each process.

[0064] As shown in Figure 4, in step S10, the control unit 40 determines whether or not the detection conditions have been met. The detection conditions include a first detection condition, a second detection condition, and a third detection condition. The control unit 40 determines that the detection conditions have been met when at least one of the first detection condition, the second detection condition, and the third detection condition has been met.

[0065] The first detection condition may be met after the power is turned on. In other words, the first detection condition may be met as soon as the power is turned on. The second detection condition may be met when a read command is input. In other words, the second detection condition may be met after a read command is input but before an image is read from the original document D. The third detection condition may be met after a read command is input and while multiple original documents D are being read. In other words, when transporting the first original document and the second original document that follows the first, the third detection condition may be met after a read command is input, after an image has been read from the first original document, and before an image has been read from the second original document. To put it another way, the third detection condition may be met after a read command is input and during the period between reading images from multiple original documents D.

[0066] The control unit 40 may determine that the first detection condition has been met after executing a predetermined process, provided that the power has been turned on. In other words, the control unit 40 may determine that the first detection condition has been met upon power-on. When a reading instruction is input, the control unit 40 may determine that the second detection condition has been met before detecting the leading edge of the document D based on the detection result of the third document detection unit 30. The control unit 40 may determine that the third detection condition has been met when it detects the trailing edge of the document D based on the detection result of the third document detection unit 30. The control unit 40 may determine that the third detection condition has been met after a predetermined time has elapsed following the detection of the trailing edge of the document D based on the detection result of the third document detection unit 30.

[0067] The control unit 40 terminates the power load detection process if it determines that the detection conditions are not met. On the other hand, if the control unit 40 determines that the detection conditions are met, it proceeds to step S11.

[0068] In step S11, the control unit 40 performs a speed acquisition process. In this process, the control unit 40 acquires a first rotational speed as the rotational speed of the second drive unit 26. The first rotational speed is the rotational speed corresponding to the first transport speed as the transport speed of the document D. The first rotational speed may be a predetermined rotational speed. In this case, the first rotational speed may be the rotational speed corresponding to the fastest transport speed of the image reading device 10. The first rotational speed may also be the rotational speed corresponding to the transport speed of the image reading device 10 included in the reading instruction when the second detection condition or the third detection condition is met. When this process is completed, the control unit 40 proceeds to step S12.

[0069] In step S12, the control unit 40 performs a threshold acquisition process. In this process, the control unit 40 acquires a first threshold TH1 corresponding to the first rotational speed acquired in step S11. The control unit 40 also acquires a second threshold TH2 regardless of the first rotational speed. When this process is completed, the control unit 40 proceeds to step S13.

[0070] In step S13, the control unit 40 executes motor drive processing. In this processing, the control unit 40 drives the second drive unit 26 at the first rotational speed acquired in step S11. In particular, the control unit 40 drives the second drive unit 26 at the first rotational speed based on the signal from the position detection unit 27. When the first detection condition is met, the control unit 40 may execute motor drive processing as initial operation processing accompanying power-on. When the third detection condition is met, the control unit 40 may execute motor drive processing as document transport processing according to the reading instruction. When this processing is completed, the control unit 40 moves to step S14.

[0071] In step S14, the control unit 40 performs a power load value acquisition process. In this process, the control unit 40 acquires the power load value of the second drive unit 26 based on the current value output to the second drive unit 26. When this process is completed, the control unit 40 proceeds to step S15.

[0072] In step S15, the control unit 40 executes a power load determination process. As will be described in detail later, in this process, the control unit 40 determines the power load value of the second drive unit 26 obtained in step S14 based on the first threshold TH1 and second threshold TH2 obtained in step S12. When this process is completed, the control unit 40 terminates the power load detection process.

[0073] <Power load determination process> Next, the power load determination process will be explained with reference to Figure 5. As shown in Figure 5, in step S31, the control unit 40 determines whether the power load value of the second drive unit 26 obtained in step S14 exceeds the second threshold TH2. If the control unit 40 determines that the power load value of the second drive unit 26 exceeds the second threshold TH2, it proceeds to step S32. On the other hand, if the control unit 40 determines that the power load value of the second drive unit 26 does not exceed the second threshold TH2, it proceeds to step S34.

[0074] In step S32, the control unit 40 performs transport restriction processing. In this process, the control unit 40 stores information restricting the transport of the original document D in memory. As a result, the control unit 40 restricts the reading of images from the original document D. Specifically, the control unit 40 stops reading images in response to a reading instruction when the second or third detection condition is met. When this process is completed, the control unit 40 proceeds to step S33.

[0075] Thus, the control unit 40 controls the second drive unit 26 to transport the document D at the first transport speed, and after determining that the power load value of the second drive unit 26 exceeds the second threshold TH2, it controls the second drive unit 26 to restrict the transport of the document D.

[0076] In step S33, the control unit 40 executes a restriction notification process. In this process, the control unit 40 causes the notification unit 19 to notify information indicating a restriction on transport. Specifically, the control unit 40 displays information indicating a restriction on transport on the display unit. The control unit 40 may also display information on the display unit prompting contact with the support center. The control unit 40 may also display information on the display unit prompting repair of the image reading device 10 and replacement of the image reading device 10. When this process is completed, the control unit 40 terminates the power load determination process.

[0077] In step S34, the control unit 40 determines whether the power load value of the second drive unit 26 obtained in step S14 exceeds the first threshold TH1. If the control unit 40 determines that the power load value of the second drive unit 26 exceeds the first threshold TH1, it proceeds to step S35. On the other hand, if the control unit 40 determines that the power load value of the second drive unit 26 does not exceed the first threshold TH1, it terminates the power load determination process. In other words, the control unit 40 controls the second drive unit 26 so that the document D can be transported at the first transport speed.

[0078] In step S35, the control unit 40 performs a speed reduction notification process. In this process, the control unit 40 causes the notification unit 19 to notify the selection information. Specifically, the control unit 40 displays the selection information on the display unit. The selection information may be information that allows the user to select whether or not to transport the document D at the second transport speed. The selection information may also be information that allows the user to select whether or not to reduce the transport speed. The second transport speed is a transport speed lower than the first transport speed. The second transport speed may be a transport speed lower than the first transport speed by a predetermined speed. The second transport speed may be greater than speed v2. The second transport speed may be the same as speed v2. The second transport speed may be less than speed v2. When this process is completed, the control unit 40 moves the process to step S36.

[0079] Thus, when the control unit 40 controls the second drive unit 26 to transport the document D at the first transport speed and determines that the power load value of the second drive unit 26 exceeds the first threshold TH1, it displays the selection information on the display unit.

[0080] In step S36, the control unit 40 waits for instructions from the user and determines whether the user's instructions are to reduce the transport speed. If the control unit 40 determines that the user's instructions are not to reduce the transport speed, it proceeds to step S32. In other words, the control unit 40 restricts the transport of the document D if it is selected not to transport the document D at the second transport speed. On the other hand, if the control unit 40 determines that the user's instructions are to reduce the transport speed, it proceeds to step S37.

[0081] In step S37, the control unit 40 performs a deceleration speed determination process. In this process, the control unit 40 determines a second transport speed as the transport speed of the document D. When this process is completed, the control unit 40 proceeds to step S38.

[0082] In step S38, the control unit 40 performs a speed change process. In this process, the control unit 40 stores in memory information indicating that the transport speed of the document D will be the second transport speed. In other words, if the control unit 40 selects to transport the document D at the second transport speed, it can control the second drive unit 26 to transport the document D at the second transport speed. When this process is completed, the control unit 40 terminates the power load determination process.

[0083] As a result, when the first detection condition is met, the control unit 40 controls the second drive unit 26 to transport the document D at the first transport speed and detects the power load value of the second drive unit 26. Then, after the control unit 40 determines that the power load value of the second drive unit 26 exceeds the first threshold TH1, if a reading instruction is input, it can control the second drive unit 26 to transport the document D at the second transport speed.

[0084] More specifically, the control unit 40 drives the second drive unit 26 at a second rotational speed based on the signal from the position detection unit 27. The second rotational speed is the rotational speed corresponding to the second transport speed. The control unit 40 causes the reading unit 31 to read an image from the original document D at a reading operation timing corresponding to the second transport speed.

[0085] Furthermore, when the second detection condition is met, the control unit 40 detects the power load value of the second drive unit 26 while controlling the second drive unit 26 to transport the document D at the first transport speed. After determining that the power load value of the second drive unit 26 exceeds the first threshold TH1, the control unit 40 can control the second drive unit 26 to transport the document D at the second transport speed.

[0086] Furthermore, when the third detection condition is met, the control unit 40 detects the power load value of the second drive unit 26 while controlling the second drive unit 26 to transport the document D at the first transport speed. After determining that the power load value of the second drive unit 26 exceeds the first threshold TH1, the control unit 40 can control the second drive unit 26 to transport the document D at the second transport speed.

[0087] Thus, the control unit 40 can control the second drive unit 26 to transport the document D at a second transport speed after determining that the power load value of the second drive unit 26 exceeds the first threshold TH1 while the second drive unit 26 is being controlled to transport the document D at a first transport speed.

[0088] <Operation and Effects of the First Embodiment> The operation and effects of the first embodiment will now be described. (1-1) The control unit 40 can detect the power load value of the second drive unit 26. After the control unit 40 has controlled the second drive unit 26 to transport the document D at a first transport speed and has determined that the power load value of the second drive unit 26 exceeds a first threshold TH1, it can control the second drive unit 26 to transport the document D at a second transport speed that is slower than the first transport speed. Conventionally, if the second drive unit 26 deteriorates, for example due to wear of the bearings of the second drive unit 26, the power load of the second drive unit 26 increases. In such cases, in order to transport the document D at the same transport speed, the current value output to the second drive unit 26 increases, and as a result, power consumption increases. This can lead to the image reading device 10 becoming unusable, for example, due to a failure of the second drive unit 26. Of course, even if the device is approved under various laws and regulations, it is not desirable to use the image reading device 10 under different conditions. Furthermore, depending on the power supply method, such as USB (Universal Serial Bus) power supply, increased power consumption may prevent the image reading device 10 from being used properly. Therefore, with the above configuration, even if the power load value of the second drive unit 26 exceeds the first threshold TH1 due to aging deterioration of the second drive unit 26, the deterioration of the second drive unit 26 can be suppressed by transporting the document D at a second transport speed that is slower than the first transport speed. Consequently, the timing at which the image reading device 10 becomes unusable can be extended, improving user convenience.

[0089] (1-2) After the control unit 40 determines that the power load value of the second drive unit 26 exceeds the first threshold TH1 upon power-up, if a reading instruction is input, it can control the second drive unit 26 to transport the document D at the second transport speed. Therefore, if the power load value of the second drive unit 26 exceeds the first threshold TH1 due to aging deterioration of the second drive unit 26 upon power-up, the aging deterioration of the second drive unit 26 can be suppressed by transporting the document D at the second transport speed when a reading instruction is input thereafter. Consequently, the timing at which the image reading device 10 becomes unusable can be extended, improving user convenience.

[0090] (1-3) When a reading instruction is input, the control unit 40 detects the power load value of the second drive unit 26 while controlling the second drive unit 26 to transport the document D at a first transport speed, before allowing the reading unit 31 to read an image from the document D. This makes it possible to identify early on when the power load value of the second drive unit 26 exceeds the first threshold TH1 due to deterioration of the second drive unit 26 over time. Therefore, the timing at which the image reading device 10 becomes unusable can be extended, improving user convenience.

[0091] (1-4) After a reading instruction is input, the control unit 40 controls the second drive unit 26 to transport the documents D at a first transport speed during the period between reading images from multiple documents D, and detects the power load value of the second drive unit 26. Therefore, it is possible to identify early on when the power load value of the second drive unit 26 exceeds the first threshold TH1 due to deterioration of the second drive unit 26 over time. Thus, the timing at which the image reading device 10 becomes unusable can be extended, improving user convenience.

[0092] (1-5) The control unit 40 controls the second drive unit 26 to transport the document D at a first transport speed, and after determining that the power load value of the second drive unit 26 exceeds a second threshold TH2 which is greater than the first threshold TH1, it restricts the transport of the document D. Therefore, the power load value of the second drive unit 26 can be determined using both the first threshold TH1 and the second threshold TH2 which is greater than the first threshold TH1. This allows for greater versatility in the control content according to the power load value of the second drive unit 26. In particular, the transport of the document D is restricted when the power load value of the second drive unit 26 exceeds the second threshold TH2. Therefore, defects associated with the transport of the document D can be suppressed, improving user convenience.

[0093] (1-6) When the control unit 40 controls the second drive unit 26 to transport the document D at the first transport speed and determines that the power load value of the second drive unit 26 exceeds the first threshold TH1, it displays selection information on the display unit. Therefore, when it determines that the power load value of the second drive unit 26 exceeds the first threshold TH1, it is possible to provide the user with the opportunity to choose whether or not to transport the document D at a second transport speed that is slower than the first transport speed. Thus, user convenience can be improved.

[0094] (1-7) The control unit 40 can control the second drive unit 26 to transport the document D at the second transport speed when it is selected to transport the document D at the second transport speed. The control unit 40 restricts the transport of the document D when it is selected not to transport the document D at the second transport speed. Therefore, the user is given the opportunity to choose whether or not to transport the document D at the second transport speed. Thus, user convenience can be improved.

[0095] [Second Embodiment] Next, a second embodiment will be described. In the second embodiment, it is also determined whether the power load value of the second drive unit 26 exceeds the third threshold value TH3. In the following description, the same reference numerals are used for the same components as in the embodiments already described, and redundant explanations are omitted or simplified.

[0096] <Threshold for power load capacity> As shown in Figure 6, Graph 51, unlike Graph 50, is also a graph showing the third threshold TH3. The third threshold TH3 is a threshold used to determine that while the possibility of an abnormality occurring in the drive of the second drive unit 26 is low, there is a possibility of an abnormality occurring in the drive of the second drive unit 26 over time. The third threshold TH3 is a threshold that allows for the extension of the lifespan of the second drive unit 26 if the rotational speed is lower than the current rotational speed. In other words, the third threshold TH3 is a threshold that recommends setting the rotational speed lower than the current rotational speed. The third threshold TH3 shows a similar trend to the first threshold TH1, but the power load value is smaller than that of the first threshold TH1.

[0097] To give a specific example, when the rotational speed of the second drive unit 26 is speed v11, the third threshold TH3 is value Tr31 as the power load value of the second drive unit 26. Value Tr31 is smaller than value Tr11. When the rotational speed of the second drive unit 26 is speed v12, the third threshold TH3 is value Tr32 as the power load value of the second drive unit 26. Value Tr32 is smaller than value Tr12. When the rotational speed of the second drive unit 26 is speed v13, the third threshold TH3 is value Tr33 as the power load value of the second drive unit 26. Value Tr33 is smaller than value Tr13. Thus, it can be said that the third threshold TH3 is smaller than the first threshold TH1.

[0098] <Power load determination process> As shown in Figure 7, in the power load determination process, in step S34, if the control unit 40 determines that the power load value of the second drive unit 26 does not exceed the first threshold TH1, it proceeds to step S39. In step S39, the control unit 40 determines whether the power load value of the second drive unit 26 obtained in step S14 exceeds the third threshold TH3. If the control unit 40 determines that the power load value of the second drive unit 26 exceeds the third threshold TH3, it proceeds to step S40. On the other hand, if the control unit 40 determines that the power load value of the second drive unit 26 does not exceed the third threshold TH3, it terminates the power load determination process. In other words, the control unit 40 controls the second drive unit 26 so that the document D can be transported at the first transport speed.

[0099] In step S40, the control unit 40 performs a speed reduction notification process, similar to step S35. Then, in step S41, if the control unit 40 determines, similar to step S36, that the instruction from the user is an instruction to reduce the transport speed, it proceeds to step S37. On the other hand, if the control unit 40 determines that the instruction from the user is not an instruction to reduce the transport speed, it terminates the power load determination process. In other words, the control unit 40 controls the second drive unit 26 so that the document D can be transported at the first transport speed.

[0100] Thus, the control unit 40 can control the second drive unit 26 to transport the document D at a second transport speed after it has determined that the power load value of the second drive unit 26 has exceeded the third threshold TH3, while the control unit 40 has controlled the second drive unit 26 to transport the document D at a first transport speed.

[0101] <Effects of the second embodiment> The effects of the second embodiment will now be described. (2-1) The control unit 40 controls the second drive unit 26 to transport the document D at a second transport speed after determining that the power load value of the second drive unit 26 exceeds the third threshold TH3 while the control unit 40 is controlling the second drive unit 26 to transport the document D at a first transport speed. Therefore, the power load value of the second drive unit 26 can be determined using a first threshold TH1, a second threshold TH2 which is greater than the first threshold TH1, and a third threshold TH3 which is less than the first threshold TH1. This allows for greater versatility in the control content according to the power load value of the second drive unit 26. Consequently, user convenience can be improved.

[0102] [Third Embodiment] Next, a third embodiment will be described. In the third embodiment, when the first detection condition is met, the power load value is detected by different control methods depending on the presence or absence of the document D in the transport path 14.

[0103] <Power load detection process> As shown in Figure 8, in the power load detection process, in step S16, the control unit 40 determines whether or not the power has been turned on. In other words, the control unit 40 determines whether or not the first detection condition has been met. If the control unit 40 does not determine that the power has been turned on, it terminates the power load detection process. On the other hand, if the control unit 40 determines that the detection condition has been met, it proceeds to step S11.

[0104] When step S12 is completed, the control unit 40 proceeds to step S17. In step S17, the control unit 40 determines whether or not a document D has been detected in the transport path 14 based on signals from the second document detection unit 29 and the third document detection unit 30. In this process, if the control unit 40 detects the presence of document D in at least one of the second document detection unit 29 and the third document detection unit 30, it determines that document D has been detected in the transport path 14. If the control unit 40 determines that document D has not been detected in the transport path 14, it proceeds to step S18. On the other hand, if the control unit 40 determines that document D has been detected in the transport path 14, it proceeds to step S19.

[0105] In step S18, the control unit 40 sets a second time as the time to drive the second drive unit 26. The second time is the time required to detect the power load value of the second drive unit 26. When this process is completed, the control unit 40 moves on to step S13.

[0106] In step S19, the control unit 40 sets a first time as the time to drive the second drive unit 26. The first time is longer than the second time. In other words, the second time is shorter than the first time. The first time is the sum of the second time and the discharge time. The discharge time is the time required to discharge the document D from the discharge port 11B in the transport path 14. In other words, the first time can be said to be the time during which the document D can be discharged. When this process is completed, the control unit 40 moves on to step S20.

[0107] In step S20, the control unit 40 performs the motor drive process in the same way as in step S13. Then, in step S21, the control unit 40 determines whether or not the discharge time has elapsed. The control unit 40 continues to execute step S21 until it determines that the discharge time has elapsed, and if it determines that the discharge time has elapsed, it proceeds to step S14.

[0108] Thus, when the control unit 40 detects the document D in the transport path 14 upon power-up, it controls the second drive unit 26 to transport the document D at the first transport speed for a first period of time and detects the power load value of the second drive unit 26. On the other hand, when the control unit 40 does not detect the document D in the transport path 14 upon power-up, it controls the second drive unit 26 to transport the document D at the first transport speed for a second period of time, which is shorter than the first period, and detects the power load value of the second drive unit 26.

[0109] <Effects of the Third Embodiment> The effects of the third embodiment will be described. (3-1) When the control unit 40 detects a document D upon power-up, it controls the second drive unit 26 to transport the document D at a first transport speed for a first period of time during which the document D can be ejected, and detects the power load value of the second drive unit 26. Therefore, when a document D is detected upon power-up, the power load value of the second drive unit 26 can be detected using the first period during which the document D can be ejected. This allows the time for ejecting the document D and the time for detecting the power load value of the second drive unit 26 to be shared upon power-up. Consequently, processing efficiency upon power-up can be improved, and user convenience can be enhanced.

[0110] (3-2) If the document D is not detected when the power is turned on, the control unit 40 controls the second drive unit 26 to transport the document D at the first transport speed for a second time, which is shorter than the first time, and detects the power load value of the second drive unit 26. Therefore, if the document D is not detected when the power is turned on, the power load value of the second drive unit 26 can be detected using a second time, which is shorter than the first time, during which the document D can be ejected. Thus, it is possible to improve the processing efficiency when the power is turned on while providing versatility in the processing when the power is turned on, and improve user convenience.

[0111] [Fourth Embodiment] Next, a fourth embodiment will be described. In the fourth embodiment, when the control unit 40 determines that the power load value of the second drive unit 26 exceeds the first threshold TH1, it transports the document D at a transport speed lower than before and repeatedly determines whether or not the power load value of the second drive unit 26 exceeds the first threshold TH1.

[0112] As shown in Figure 9, in the power load detection process, when step S14 is completed, the control unit 40 proceeds to step S31. In step S31, if the control unit 40 determines that the power load value of the second drive unit 26 exceeds the second threshold TH2, it proceeds to step S32. On the other hand, if the control unit 40 determines that the power load value of the second drive unit 26 does not exceed the second threshold TH2, it proceeds to step S34.

[0113] In step S34, if the control unit 40 determines that the power load value of the second drive unit 26 exceeds the first threshold TH1, it proceeds to step S37. In step S37, the control unit 40 executes a reduction speed determination process. In this process, the control unit 40 determines a transport speed for the document D by reducing the transport speed by a specified transport speed from the previous transport speed. The specified transport speed is defined to correspond to the previous transport speed. The specified transport speed may be a constant speed defined for each previous transport speed, or it may be a different speed defined for each previous transport speed. The specified transport speed may be a speed that is less than or equal to the first transport speed v2, or it may be a speed that is not less than or equal to the first transport speed v2. When this process is completed, the control unit 40 proceeds to step S11 again.

[0114] As a result, the control unit 40 repeatedly determines whether the power load value of the second drive unit 26 exceeds the first threshold TH1 at a transport speed reduced by the specified transport speed. In other words, after determining that the power load value of the second drive unit 26 exceeds the first threshold TH1, the control unit 40 controls the second drive unit 26 to transport the document D at a slower transport speed than before and repeatedly determines whether the power load value of the second drive unit 26 exceeds the first threshold TH1. To put it another way, the control unit 40 repeatedly determines whether the power load value of the second drive unit 26 exceeds the first threshold TH1 at a slower transport speed than before until it is determined that the power load value of the second drive unit 26 does not exceed the first threshold TH1.

[0115] On the other hand, if the control unit 40 determines that the power load value of the second drive unit 26 does not exceed the first threshold TH1, it proceeds to step S38. In step S38, the control unit 40 executes a speed change process. In this process, the control unit 40 stores in memory information indicating the transport speed at which the power load value of the second drive unit 26 is determined not to exceed the first threshold TH1. In other words, the control unit 40 can control the second drive unit 26 to transport the document D at the transport speed at which the power load value of the second drive unit 26 is determined not to exceed the first threshold TH1. In this case, the transport speed at which the power load value of the second drive unit 26 is determined not to exceed the first threshold TH1 corresponds to an example of the second transport speed. When this process is completed, the control unit 40 terminates the power load determination process.

[0116] <Effects of the 4th Embodiment> The effects of the fourth embodiment will be described. (4-1) After the control unit 40 determines that the power load value of the second drive unit 26 exceeds the first threshold TH1, it can repeatedly determine whether the power load value of the second drive unit 26 exceeds the first threshold TH1 at a transport speed slower than the previous transport speed. Therefore, it is possible to repeatedly determine whether the power load value of the second drive unit 26 exceeds the first threshold TH1 at multiple transport speeds. As a result, by transporting the document D at an appropriate transport speed, deterioration of the second drive unit 26 over time can be suppressed. Consequently, the timing at which the image reading device 10 becomes unusable can be extended, improving user convenience.

[0117] [Fifth Embodiment] Next, a fifth embodiment will be described. In the fifth embodiment, the control unit 40 may detect the transport speed of the document D based on signals from the second document detection unit 29 and the third document detection unit 30. As a specific example, the control unit 40 determines the elapsed time from when it detects the leading edge of the document D based on the signal from the second document detection unit 29 until when it detects the leading edge of the document D based on the signal from the third document detection unit 30. The control unit 40 may then detect the transport speed of the document D based on the distance between the second document detection unit 29 and the third document detection unit 30 and the elapsed time. The control unit 40 may then acquire the power load value of the second drive unit 26 based on the transport speed of the document D and the current value output to the second drive unit 26.

[0118] In this way, the control unit 40 can acquire the power load value of the second drive unit 26 based on the actual transport speed of the document D. As a result, the control unit 40 can acquire the power load value including not only the second drive unit 26 but also the power transmission members from the second drive unit 26 to the document D. Therefore, the timing at which the image reading device 10 becomes unusable can be extended, improving user convenience. The power transmission members from the second drive unit 26 to the document D include at least one of the feed / feed separation roller 22B, the transport drive roller 23A, and the discharge drive roller 24A.

[0119] [Example of changes] This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0120] In the fourth embodiment, in step S21, the control unit 40 may detect the trailing end of the document D in the transport path 14 based on the signal from the third document detection unit 30, and determine whether or not the ejection time has elapsed since the trailing end of the document D was detected in the transport path 14. The first time does not have to be predetermined.

[0121] The control unit 40 may correct the power load value of the second drive unit 26 based on whether or not the document D is actually being transported. For example, the control unit 40 may reduce the power load value of the second drive unit 26 when the document D is actually being transported compared to when the document D is not being transported.

[0122] The image reading device 10 may include a fourth document detection unit that detects the thickness of the document D. The control unit 40 may correct the power load value of the second drive unit 26 based on the result detected by the fourth document detection unit. For example, the control unit 40 may, based on the result detected by the fourth document detection unit, reduce the power load value of the second drive unit 26 when the document D is thicker than when the document D is thin. The control unit 40 may determine the thickness of the document D based on user instructions.

[0123] The functions of the second document detection unit 29 and the third document detection unit 30 may be any functions. For example, the second document detection unit 29 may be a detection unit equipped with the function of detecting double feeding of documents D. Double feeding of documents D means that multiple documents D are transported while overlapping each other.

[0124] The positions of the second document detection unit 29 and the third document detection unit 30 can be any position. It is preferable that the second document detection unit 29 and the third document detection unit 30 be far apart, as this reduces the likelihood of detection errors in the transport speed of the document D and improves the accuracy of detecting the transport speed of the document D.

[0125] The control unit 40 may determine whether or not to reduce the transport speed based on the power load value of the second drive unit 26 when a detection condition different from the first, second, and third detection conditions is met. As a specific example, the detection condition may include a condition that is met by user instruction. The detection condition may include a condition that is met when a predetermined period of time, such as one month, has elapsed. The detection condition may include a condition that is met after the number of images read from the original document D reaches a specified number. Furthermore, a combination of these detection conditions may be used. To give a specific example, the control unit 40 may determine whether or not to reduce the transport speed based on the power load value of the second drive unit 26 when the power is turned on after the number of images read from the original document D has reached a specified number. The control unit 40 may also determine whether or not to reduce the transport speed based on the power load value of the second drive unit 26 when a read instruction is input after a predetermined period of time has elapsed.

[0126] The control unit 40 may control the transport of the document D at the second transport speed when the first detection condition is met, before a read instruction is input. In other words, the control unit 40 may control the transport of the document D at the second transport speed when the first detection condition is met, before the read process based on the input of a read instruction.

[0127] The control unit 40 may output selection information from at least one of the display unit, audio output unit, and light-emitting unit. In other words, the control unit 40 may output selection information from the notification unit 19. The control unit 40 may also cause the terminal display unit 103 of the terminal device 100 to display the selection information.

[0128] The control unit 40 may select whether or not to reduce the transport speed based on the user's instructions, or it may automatically reduce the transport speed without user instructions. The control unit 40 may, upon user instruction, reset the setting if it has set the transport speed to be reduced based on the power load value of the second drive unit 26. In other words, the control unit 40 may, upon user instruction, maintain the setting if it has set the transport speed to be reduced based on the power load value of the second drive unit 26. The control unit 40 may, upon user instruction, reset the setting upon input of the next reading instruction if it has set the transport speed to be reduced based on the power load value of the second drive unit 26. The control unit 40 may, upon user instruction, reset the setting after the next power-on if it has set the transport speed to be reduced based on the power load value of the second drive unit 26.

[0129] The control unit 40 may, if it has set the transport speed to decrease based on the power load value of the second drive unit 26, reset the setting upon the next input of a reading instruction, regardless of the user's instructions. The control unit 40 may, if it has set the transport speed to decrease based on the power load value of the second drive unit 26, reset the setting after the next power-on, regardless of the user's instructions.

[0130] - When the control unit 40 is set to reduce the transport speed based on the power load value of the second drive unit 26, it may reset the setting upon input of the next read instruction and then determine again whether or not to reduce the transport speed based on the power load value of the second drive unit 26. In this case, if the frequency of determining whether or not to reduce the transport speed based on the power load value of the second drive unit 26 is increased, the determination can be made based on the latest power load value of the second drive unit 26. On the other hand, if the frequency of determining whether or not to reduce the transport speed based on the power load value of the second drive unit 26 is decreased, the control load, such as acquiring the power load value of the second drive unit 26, can be suppressed.

[0131] The first transport speed may be the transport speed of the original document D when the reading resolution is relatively high. If the transport speed is set to decrease based on the power load value of the second drive unit 26, the first transport speed may be the decreased transport speed. In other words, the control unit 40 may specify the decreased transport speed as the first transport speed.

[0132] The second transport speed may be the transport speed when the reading resolution is relatively high. The second transport speed may be faster than the transport speed when the reading resolution is relatively high. The second transport speed may be slower than the transport speed when the reading resolution is relatively high.

[0133] The specified transport speed may be the difference between the transport speed when the reading resolution is relatively low and the transport speed when the reading resolution is relatively high. The specified transport speed may be greater than the difference between the transport speed when the reading resolution is relatively low and the transport speed when the reading resolution is relatively high. The specified transport speed may be less than the difference between the transport speed when the reading resolution is relatively low and the transport speed when the reading resolution is relatively high.

[0134] The control unit 40 may determine at least one of the first transport speed, second transport speed, and specified transport speed according to the user's specifications. The image reading device 10 may be equipped with at least one of the following rollers: a paper feed roller 21, a pair of feeding rollers 22, a pair of transport rollers 23, and a pair of discharge rollers 24, but may also be equipped with other rollers. Any roller may also be used to reduce the transport speed based on the power load value.

[0135] The image reading device 10 may be equipped with at least one of the first drive unit 25 and the second drive unit 26 as a DC motor, or it may be equipped with other DC motors. The control unit 40 may, for example, control the rotational speed of the first drive unit 25 based on the power load value of the first drive unit 25, and may also target DC motors other than the first drive unit 25 and the second drive unit 26.

[0136] The image sensor 33 is not limited to a CMOS image sensor, but may also be a MOS image sensor or a CCD image sensor. The image sensor 33 is not limited to a linear image sensor, but may also be an area image sensor.

[0137] The material of the manuscript is not limited to paper; it may also be made of resin film or sheet, fabric, metal film, etc. The image reading device 10 may be part of a multifunction device that has a scanner function as well as a printing function and a copying function. The present invention has been applied to the image reading device 10, but is not limited thereto. For example, the present invention may be applied to a recording device. The recording device comprises a recording unit that records on a medium, a DC motor, rollers, and a control unit. The rollers are configured to transport the medium. The control unit is configured to record on the medium at a timing corresponding to the transport speed.

[0138] As used herein, the expression "at least one of" means one or more of the desired options. For example, as used herein, if there are two options, the expression "at least one of" means either one option or both of the two options. As another example, as used herein, if there are three or more options, the expression "at least one of" means either one option or any combination of two or more options.

[0139] [Note] The technical concepts and their effects that can be understood from the embodiments and modifications described above are described below.

[0140] (A) The image reading device comprises a DC motor, rollers driven by the DC motor, a reading unit capable of reading an image from a document transported by the rollers, and a control unit capable of controlling the drive of the DC motor, wherein the control unit is capable of detecting the power load value of the DC motor, and after the control unit has controlled the DC motor to transport a document at a first transport speed and has determined that the power load value of the DC motor has exceeded a first threshold, it is possible to control the DC motor to transport the document at a second transport speed that is slower than the first transport speed.

[0141] With this configuration, even if the power load value of the DC motor exceeds the first threshold due to aging degradation of the DC motor, the degradation of the DC motor can be suppressed by transporting the document at a second transport speed that is slower than the first transport speed. Therefore, the timing at which the image reading device becomes unusable can be extended, further improving user convenience.

[0142] (B) In the image reading device described above, the control unit may, after determining that the power load value of the DC motor exceeds the first threshold while the DC motor is controlled to transport the document at the first transport speed upon power-on, control the DC motor to transport the document at the second transport speed when a reading instruction is input.

[0143] With this configuration, if the power load value of the DC motor exceeds the first threshold due to aging deterioration upon power-up, the document will be transported at the second transport speed when a reading instruction is subsequently input, thereby suppressing the aging deterioration of the DC motor. Therefore, the timing at which the image reading device becomes unusable can be extended, improving user convenience.

[0144] (C) The above image reading device includes a document detection unit capable of detecting a document being transported, and the control unit may, when a document is detected by the document detection unit upon power-up, control the DC motor to transport the document at the first transport speed for a first time period during which the document can be ejected, and detect the power load value of the DC motor.

[0145] With this configuration, when a document is detected upon power-up, the power load value of the DC motor can be detected during the first time period in which the document can be ejected. This allows the time for ejecting the document and the time for detecting the power load value of the DC motor to be shared upon power-up. Therefore, processing efficiency upon power-up can be improved, and user convenience can be enhanced.

[0146] (D) The image reading device includes a document detection unit capable of detecting a document being transported, and the control unit may, when a document is detected by the document detection unit upon power-up, control the DC motor to transport the document at the first transport speed for a first time period during which the document can be ejected, and detect the power load value of the DC motor; or, when a document is not detected by the document detection unit upon power-up, control the DC motor to transport the document at the first transport speed for a second time period shorter than the first time, and detect the power load value of the DC motor.

[0147] This configuration can achieve the same effect as (C). On the other hand, if no document is detected upon power-on, the power load value of the DC motor can be detected using a second time, which is shorter than the first time during which the document can be ejected. Therefore, it is possible to improve the processing efficiency associated with power-on while allowing for variability in the processing associated with power-on, thereby improving user convenience.

[0148] (E) In the image reading device described above, when a reading instruction is input, the control unit may, before causing the reading unit to read an image from the document, control the DC motor to transport the document at the first transport speed and detect the power load value of the DC motor.

[0149] This configuration allows for early detection of when the power load value of the DC motor exceeds the first threshold due to aging. Therefore, the timing at which the image reading device becomes unusable can be extended, improving user convenience.

[0150] (F) In the image reading device described above, the control unit may, after a reading instruction has been input, after the reading unit has read an image from the first document, and before the reading unit has read an image from the second document following the first document, control the DC motor to transport the document at the first transport speed and detect the power load value of the DC motor.

[0151] This configuration allows for early detection of when the power load value of the DC motor exceeds the first threshold due to aging. Therefore, the timing at which the image reading device becomes unusable can be extended, improving user convenience.

[0152] (G) In the image reading device described above, the control unit may restrict the transport of the document after determining that the power load value of the DC motor exceeds a second threshold value which is greater than the first threshold value while the DC motor is controlled to transport the document at the first transport speed.

[0153] This configuration allows for the determination of the DC motor's power load value using both a first threshold and a second threshold greater than the first threshold. This enables greater versatility in the control settings based on the DC motor's power load value. In particular, when the DC motor's power load value exceeds the second threshold, document transport is restricted. Therefore, defects associated with document transport can be prevented, improving user convenience.

[0154] (H) The image reading device may include a display unit capable of displaying information, and when the control unit has controlled the DC motor to transport the document at the first transport speed and has determined that the power load value of the DC motor exceeds the first threshold, it may display selection information on the display unit to allow the user to choose whether or not to transport the document at the second transport speed.

[0155] This configuration allows the user to choose whether or not to transport the document at a second transport speed, which is slower than the first transport speed, when it is determined that the power load value of the DC motor exceeds a first threshold. Therefore, user convenience can be improved.

[0156] (I) In the image reading device described above, the control unit can control the DC motor to transport the document at the second transport speed when it is selected to transport the document at the second transport speed, and may restrict the transport of the document when it is selected not to transport the document at the second transport speed.

[0157] This configuration allows the user to choose whether or not to transport the document at the second transport speed. Therefore, user convenience can be improved. (J) In the image reading device described above, the control unit may, after determining that the power load value of the DC motor exceeds the first threshold, repeatedly determine whether the power load value of the DC motor exceeds the first threshold while controlling the DC motor to transport the document at a transport speed slower than the previous transport speed.

[0158] This configuration allows for repeated determination of whether the power load value of the DC motor exceeds a first threshold at multiple transport speeds. This suppresses the aging degradation of the DC motor by transporting documents at an appropriate speed. Therefore, the time at which the image reader becomes unusable can be extended, improving user convenience.

[0159] (K) In the image reading device described above, the control unit may, after determining that the power load value of the DC motor exceeds a third threshold which is smaller than the first threshold while the DC motor is controlled to transport the document at the first transport speed, control the DC motor to transport the document at the second transport speed.

[0160] This configuration allows for the determination of the DC motor's power load value using a first threshold, a second threshold greater than the first threshold, and a third threshold less than the first threshold. This enables greater versatility in control settings based on the DC motor's power load value, thereby improving user convenience.

[0161] (L) An image reading method for an image reading device comprises a DC motor, rollers driven by the DC motor, a reading unit capable of reading an image from a document transported by the rollers, and a control unit capable of controlling the drive of the DC motor, wherein the control unit can control the DC motor to transport the document at a second transport speed slower than the first transport speed after determining that the power load value of the DC motor exceeds a first threshold when controlling the DC motor to transport the document at a first transport speed. This configuration can achieve the same effect as (A). [Explanation of symbols]

[0162] D...Document, SA...Scanning area, TH1...First threshold, TH2...Second threshold, TH3...Third threshold, X...Width direction, Y...Conveying direction, 10...Image reader, 11...Housing, 11A...Feed port, 11B...Outlet port, 12...Main unit, 13...Cover unit, 14...Conveying path, 15...Document support, 16...Feeding guide, 17...Stacker, 18...Operation unit, 19...Notification unit, 20...Conveying unit, 21...Paper feed roller, 22...Feeding roller pair, 22A...Feeding drive roller, 22B...Feeding separation roller, 23...Conveying roller pair, 23A...Feeding drive roller, 23B...Feeding driven roller, 24...Outlet roller pair, 24A...Outlet drive roller, 24B...Outlet driven roller, 25...First drive unit, 26... 27... Position detection unit, 28... First document detection unit, 29... Second document detection unit, 30... Third document detection unit, 31... Reading unit, 31A... First reading unit, 31B... Second reading unit, 32... Light source, 32A... First light source, 32B... Second light source, 33... Image sensor, 33A... First image sensor, 33B... Second image sensor, 34... Background plate, 34A... First background plate, 34B... Second background plate, 40... Control unit, 41... Main control unit, 42... Transport control unit, 43... Reading control unit, 44... Image processing unit, 45... Timing generator, 46... Analog front end, 50, 51... Graph, 100... Terminal device, 101... Terminal control unit, 102... Terminal operation unit, 103... Terminal display unit.

Claims

1. DC motor and A roller driven by the aforementioned DC motor, A reading unit capable of reading an image from a document conveyed by the rollers, A control unit capable of controlling the drive of the DC motor, Equipped with, The control unit is capable of detecting the power load value of the DC motor, The control unit can, after determining that the power load value of the DC motor exceeds a first threshold while the DC motor is controlled to transport the document at a first transport speed, control the DC motor to transport the document at a second transport speed slower than the first transport speed. An image reading device characterized by the following:

2. In the image reading device according to claim 1, The control unit, after determining that the power load value of the DC motor exceeds the first threshold while controlling the DC motor to transport the document at the first transport speed upon power-on, can control the DC motor to transport the document at the second transport speed when a reading instruction is input. An image reading device characterized by the following:

3. In the image reading device according to claim 2, Equipped with a document detection unit capable of detecting the document being transported, When a document is detected by the document detection unit upon power-up, the control unit controls the DC motor to transport the document at the first transport speed for a first period of time during which the document can be ejected, and detects the power load value of the DC motor. An image reading device characterized by the following:

4. In the image reading device according to claim 2, Equipped with a document detection unit capable of detecting the document being transported, When a document is detected by the document detection unit upon power-up, the control unit controls the DC motor to transport the document at the first transport speed for a first period of time during which the document can be ejected, and detects the power load value of the DC motor. If the document detection unit does not detect a document upon power-on, the control unit controls the DC motor to transport the document at the first transport speed for a second time period shorter than the first time period, and detects the power load value of the DC motor. An image reading device characterized by the following:

5. In the image reading device according to claim 1, When a reading instruction is input, the control unit, before allowing the reading unit to read an image from the document, controls the DC motor to transport the document at the first transport speed and detects the power load value of the DC motor. An image reading device characterized by the following:

6. In the image reading device according to claim 1, The control unit, after a reading instruction has been input, and during the period after the reading unit has read an image from the first document and before the reading unit has read an image from the second document following the first document, controls the DC motor to transport the document at the first transport speed and detects the power load value of the DC motor. An image reading device characterized by the following:

7. In the image reading device according to any one of claims 1 to 6, The control unit controls the DC motor to transport the document at the first transport speed, and after determining that the power load value of the DC motor exceeds a second threshold greater than the first threshold, it restricts the transport of the document. An image reading device characterized by the following:

8. In the image reading device according to any one of claims 1 to 6, Equipped with a display unit capable of displaying information, When the control unit controls the DC motor to transport the document at the first transport speed and determines that the power load value of the DC motor exceeds the first threshold, it displays selection information on the display unit for the user to choose whether or not to transport the document at the second transport speed. An image reading device characterized by the following:

9. In the image reading device according to claim 8, The control unit can control the DC motor to transport the document at the second transport speed when it is selected to transport the document at the second transport speed, and restricts the transport of the document when it is selected not to transport the document at the second transport speed. An image reading device characterized by the following:

10. In the image reading device according to any one of claims 1 to 6, The control unit can repeatedly determine whether the power load value of the DC motor exceeds the first threshold value while controlling the DC motor to transport the document at a transport speed slower than the previous transport speed after determining that the power load value of the DC motor exceeds the first threshold value. An image reading device characterized by the following:

11. In the image reading device according to any one of claims 1 to 6, The control unit can, after determining that the power load value of the DC motor exceeds a third threshold smaller than the first threshold while the DC motor is controlled to transport the document at the first transport speed, control the DC motor to transport the document at the second transport speed. An image reading device characterized by the following:

12. An image reading method for an image reading apparatus comprising a DC motor, rollers driven by the DC motor, a reading unit capable of reading an image from a document conveyed by the rollers, and a control unit capable of controlling the drive of the DC motor, When the control unit controls the DC motor to transport the document at a first transport speed, it can control the DC motor to transport the document at a second transport speed slower than the first transport speed after determining that the power load value of the DC motor has exceeded a first threshold. An image reading method for an image reading device characterized by the above.

Images