Image reading device

Abstract

To provide an image reading apparatus capable of generating data of images with a resolution desired by a user even when a transportation speed of an original is varied.SOLUTION: The image reading apparatus comprises: a transport device 20 that transports an original; and reading parts 31 and 32 for reading images on the original transported. An operation for reading an image when specific setting information is not input to a control device 60 of the image reading apparatus is defined as a first reading mode and an operation for reading an image when the specific setting information is input to the control device 60 is defined as a second reading mode. In such a case, in the second reading mode, image data of images with a resolution equal to that in the first reading mode are generated even while the reading parts 31 and 32 are caused to read images from the original that is transported by the transport device 20 at a lower speed than that in the first reading mode.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an image reading apparatus including a reading unit that reads an image of a document being conveyed by a conveyance unit.

Background Art

[0002] Patent Document 1 describes an example of an image reading apparatus that conveys a document set in a setting unit to a predetermined reading position and reads an image of the document conveyed to the reading position by a reading unit.

[0003] By the way, when conveying a color document, conveyance failures such as paper jams are more likely to occur than when conveying a monochrome document. Therefore, in the image reading apparatus described in Patent Document 1, when reading an image of a color document, the document is conveyed at a lower speed than when reading an image of a monochrome document. Specifically, in the control device of the image reading apparatus, when information based on a user operation is input, it is determined whether to read an image of a color document or an image of a monochrome document. Then, a normal conveyance mode is selected when reading an image of a monochrome document, and a conveyance mode for low-speed conveyance is selected when reading an image of a color document, which is lower than the normal conveyance mode. The conveyance unit is operated in the conveyance mode thus selected.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in an image reading apparatus, it may be necessary to read images of various originals with different thicknesses. When transporting a thin original, conveyance failures such as paper jams are more likely to occur than when transporting a thick original. Therefore, when reading the image of a thin original, it is desirable to transport the original at a lower speed than when reading the image of a thick original.

[0006] However, in an image reading apparatus that causes a reading unit to read an image of an original being transported by a transport unit, generally, there is a correlation between the transport speed of the original and the resolution of the acquired image. Specifically, the smaller the transport speed of the original, the higher the resolution of the image data generated. Therefore, when changing the transport speed of the original according to the thickness of the original, the generated image data is not necessarily the data of an image with the resolution desired by the user.

[0007] An object of the present invention is to provide an image reading apparatus capable of generating image data of an image with a resolution desired by a user even when the transport speed of an original is variable.

Means for Solving the Problems

[0008] An image reading apparatus for achieving the above object includes a conveyance unit that conveys a document, a reading unit that reads an image of the document conveyed by the conveyance unit, and a control unit that generates image data which is data of the image read by the reading unit. In the image reading apparatus, when the document is being conveyed by the conveyance unit, the reading unit reads an image of the document at predetermined timing. When specific setting information is not input to the control unit, the operation of reading an image from the document is set as a first reading mode, and when the specific setting information is input to the control unit, the operation of reading an image from the document is set as a second reading mode. In the first reading mode, the control unit causes the reading unit to read an image from the document conveyed by the conveyance unit at a speed corresponding to a required resolution, and generates image data of the image read by the reading unit. In the second reading mode, while causing the reading unit to read an image from the document conveyed by the conveyance unit at a lower speed than in the case of the first reading mode, the control unit delays the timing compared to the case of the first reading mode, so as to generate image data of an image having the same resolution as in the case of the first reading mode. When starting to read an image based on the next job in a situation where the second reading mode is selected, the control unit switches the reading mode to be implemented from the second reading mode to the first reading mode.

[0009] According to the above configuration, when an image reading is instructed in a situation where the specific setting information is not input to the control unit, the first reading mode is implemented. That is, when the user recognizes that the thickness of the document is not thin, the image reading is instructed to the image reading apparatus by the user without performing a user operation such that the specific setting information is input to the control unit. At this time, the resolution of the image based on the generated image data can be selected by the user when the user inputs an instruction for reading. Therefore, the document is conveyed at a conveyance speed correlated with the resolution required by the user, and image data of an image having the resolution required by the user is generated. Accordingly, it is possible to provide the user with image data of an image having the resolution desired by the user.

[0010] On the other hand, when image reading is instructed under the situation where the above specific setting information is input to the control unit, the second reading mode is implemented. That is, when the user recognizes that the thickness of the document is thin, after a user operation is performed such that the above specific setting information is input to the control unit, the user instructs the image reading apparatus to read an image. At this time, although the document is conveyed at a lower speed than in the case of the first reading mode, image data of an image with the same resolution as in the case of the first reading mode is generated. That is, it is possible to provide the user with image data that does not depend on the conveyance speed of the document while suppressing conveyance failures such as paper jams. Therefore, even when the conveyance speed of the document is variable, it becomes possible to generate data of an image with the resolution desired by the user.

[0011] In the above image reading apparatus, when the control unit continuously reads images of a plurality of documents, if the above specific setting information is input while the conveyance unit is conveying one of the documents among the respective documents, it is preferable to switch the reading mode to be implemented from the first reading mode to the second reading mode at the start of reading of the image of the document next to the one document.

[0012] According to the above configuration, when continuously reading images of a plurality of documents, if the above specific setting information is input to the control unit while one of the documents is being conveyed, the first reading mode is continued until the reading of the image of the one document is completed. That is, during the conveyance of one document, the reading mode is not changed and the conveyance speed of the same document is not changed. Therefore, it is possible to suppress an increase in the control load caused by the switching of the reading mode during the reading of the image.

[0013] After that, when reading the image of the next document, the second reading mode is implemented instead of the first reading mode. That is, when reading the image of a document after a certain document, the document is conveyed at a low speed. Moreover, since it is the second reading mode, even if the document is conveyed at a low speed, image data with the same resolution as in the case of the first reading mode is generated. Therefore, when reading the image of a document after the certain document, it is possible to provide the user with image data that does not depend on the conveyance speed while suppressing the occurrence of conveyance failure of the document by conveying the document at a low speed.

[0014] Also, in an image reading apparatus for achieving the above object, in an image reading apparatus including a conveyance unit that conveys a document, a reading unit that reads an image of the document conveyed by the conveyance unit, and a control unit that generates image data that is the data of the image read by the reading unit, when the operation of reading an image from a document when the thickness of the document conveyed by the conveyance unit is not thin is defined as the first reading mode, and the operation of reading an image from a document when the thickness of the document conveyed by the conveyance unit is thin is defined as the second reading mode, the control unit causes the reading unit to read an image from the document conveyed by the conveyance unit at a speed corresponding to the required resolution in the first reading mode, and generates image data of the image read by the reading unit, and in the second reading mode, while causing the reading unit to read an image from the document conveyed by the conveyance unit at a lower speed than in the case of the first reading mode, generates image data of an image with the same resolution as in the case of the first reading mode. Note that "when the thickness of the document is not thin" means when the thickness of the document is not less than the specified thickness, and "when the thickness of the document is thin" means when the thickness of the document is less than the specified thickness.

[0015] According to the above configuration, when the thickness of the document being conveyed by the conveyance unit is not thin, the first reading mode is implemented. When the user instructs the image reading device to read the image of the document, the resolution of the image based on the generated image data can be selected by the user. Therefore, it is possible to provide the user with image data of the resolution desired by the user.

[0016] On the other hand, when the thickness of the document being conveyed by the conveyance unit is thin, the second reading mode is implemented. In this case, although the document is conveyed at a lower speed than in the case of the first reading mode, image data of the same resolution as in the case of the first reading mode is generated. That is, it is possible to provide the user with image data that does not depend on the conveyance speed of the document while suppressing conveyance failures such as paper jams. Therefore, even when the conveyance speed of the document is variable, it is possible to generate image data of the resolution desired by the user.

[0017] The above image reading device includes a sound wave sensor that outputs sound waves to the document being conveyed by the conveyance unit and detects the attenuation rate of the sound waves. When the attenuation rate of the sound waves detected by the sound wave sensor is less than the determination attenuation rate under the condition that the document is being conveyed by the conveyance unit, the control unit preferably determines that the thickness of the document being conveyed by the conveyance unit is thin and implements the second reading mode.

[0018] The thinner the thickness of the document, the easier it is for the attenuation rate of the sound waves detected by the sound wave sensor to be small. Therefore, in the above configuration, when the attenuation rate of the sound waves detected by the sound wave sensor is less than the determination attenuation rate, it is possible to determine that the thickness of the document being conveyed is thin, and thus the second reading mode is implemented. By using the detection result by the sound wave sensor in this way, the second reading mode can be automatically selected and implemented.

[0019] In the above image reading apparatus, the acoustic sensor is a sensor that detects whether a plurality of original documents are being conveyed in an overlapping state, and a double-feed detection attenuation rate greater than the determination attenuation rate is provided as a threshold for determining whether a plurality of original documents are being conveyed in an overlapping state. When the attenuation rate of the sound wave detected by the acoustic sensor is equal to or greater than the determination attenuation rate and less than the double-feed detection attenuation rate under the condition that the original document is being conveyed by the conveyance unit, the first reading mode is implemented. When the attenuation rate of the sound wave detected by the acoustic sensor is equal to or greater than the double-feed detection attenuation rate under the condition that the original document is being conveyed by the conveyance unit, it is preferable to stop the conveyance of the original document by the conveyance unit and the reading of the image by the reading unit.

[0020] When a plurality of original documents are conveyed in an overlapping state, the attenuation rate of the sound wave detected by the acoustic sensor is more likely to be greater than when only one original document is being conveyed. And the attenuation rate of the sound wave when two thin original documents are overlapping is greater than the attenuation rate of the sound wave when one non-thin original document is being conveyed. Therefore, according to the above configuration, the double-feed detection attenuation rate, which is a threshold for determining whether a plurality of original documents are being conveyed in an overlapping state, is determined to be a value greater than the determination attenuation rate. And by using this double-feed detection attenuation rate, it is possible to discriminate whether one non-thin original document is being conveyed or a plurality of original documents are being conveyed in an overlapping state. And by adopting such discrimination results, it becomes possible to appropriately drive the image reading apparatus according to the situation.

[0021] In the above image reading apparatus, the conveyance unit has a pair of conveyance rollers located upstream of the reading unit in the conveyance direction of the original document, and a delivery roller arranged upstream of the pair of conveyance rollers in the conveyance direction of the original document for sending the original document toward the pair of conveyance rollers. The acoustic sensor is preferably arranged between the delivery roller and the pair of conveyance rollers in the conveyance direction of the original document.

[0022] According to the above configuration, it becomes possible to determine whether the thickness of the document being conveyed is thin or not on the upstream side in the conveyance direction from the reading unit. In the above image reading apparatus, when a predetermined end condition is satisfied under the situation where the control unit has selected the second reading mode, it is preferable that the control unit switches the reading mode to be implemented from the second reading mode to the first reading mode.

[0023] According to the above configuration, when the implementation of the second reading mode becomes unnecessary, the mode can be switched from the second reading mode to the first reading mode. In the above image reading apparatus, when setting information indicating the end of the second reading mode is input under the situation where the control unit has selected the second reading mode, it is preferable that the control unit switches the reading mode to be implemented at the time of reading the next image from the second reading mode to the first reading mode.

[0024] According to the above configuration, when setting information indicating that the implementation of the second reading mode is unnecessary is input, the first reading mode can be implemented at the time of reading the next image. In the above image reading apparatus, when starting to read an image based on the next job under the situation where the control unit has selected the second reading mode, it is preferable that the control unit switches the reading mode to be implemented from the second reading mode to the first reading mode.

[0025] According to the above configuration, at the time of reading an image based on the next job, the first reading mode can be automatically implemented. An image reading system for achieving the above object includes a conveyance unit that conveys a document, and a reading unit that reads an image of the document conveyed by the conveyance unit. The reading unit has a first reading unit disposed on one side across a conveyance path along which the document is conveyed, and a second reading unit disposed on the other side. The image reading system further includes an image reading apparatus including the conveyance unit and the reading unit, and an external device capable of communicating with the image reading apparatus. When the document is being conveyed by the conveyance unit, the reading unit reads an image of the document at predetermined intervals, and by delaying the predetermined timing, the resolution of the image read by the reading unit can be changed. When generating image data of an image with a first resolution, the conveyance unit conveys the document at a first conveyance speed when specific setting information, which is information indicating that the user has requested slow conveyance of the document from the external device, is not input. When the specific setting information is input from the external device, the conveyance unit conveys the document at a second conveyance speed that is lower than the first conveyance speed. When generating image data of an image with a second resolution that is higher than the first resolution, the conveyance unit conveys the document at a third conveyance speed that is lower than the first conveyance speed regardless of whether the specific setting information is input from the external device.

[0026] An image reading system for achieving the above object includes a conveying unit that conveys a document, and a reading unit that reads an image of the document conveyed by the conveying unit. The reading unit has a first reading unit disposed on one side across a conveying path along which the document is conveyed, and a second reading unit disposed on the other side. The image reading system further includes an image reading apparatus including the reading unit, and an external device capable of communicating with the image reading apparatus. The reading unit is capable of performing a process of reducing the resolution of the read image. When generating image data of an image with a first resolution, the conveying unit conveys the document at a first conveying speed in a state where specific setting information, which is information indicating that a user has requested slow conveyance of the document from the external device, is not input. When the specific setting information is input from the external device, the conveying unit conveys the document at a second conveying speed lower than the first conveying speed. When generating image data of an image with a second resolution higher than the first resolution, the conveying unit conveys the document at a third conveying speed lower than the first conveying speed regardless of whether the specific setting information is input from the external device.

[0027] An image reading control method for achieving the above object is an image reading control method that reads an image of a document conveyed by a conveyance unit that conveys the document, and causes a control unit to generate image data that is data of the image read by the reading unit. The method includes: a step of causing the reading unit to read the image of the document at predetermined timing; a step of changing the resolution of the image data generated by the control unit by delaying the timing; a step of causing the conveyance unit to convey the document at a first conveyance speed and causing the control unit to generate image data of an image with a first resolution when specific setting information, which is information indicating that slow conveyance of the document is required by the user, is not input to the control unit; a step of causing the conveyance unit to convey the document at a second conveyance speed that is lower than the first conveyance speed and causing the control unit to generate image data of an image with the first resolution when the specific setting information is input; a step of causing the conveyance unit to convey the document at a third conveyance speed that is lower than the first conveyance speed and causing the control unit to generate image data of an image with a second resolution that is higher than the first resolution when the specific setting information is not input; and a step of causing the conveyance unit to convey the document at the third conveyance speed and causing the control unit to generate image data of the image with the second resolution when the specific setting information is input.

[0028] An image reading control method for achieving the above object is an image reading control method for reading an image of a document conveyed by a conveyance unit that conveys the document, and generating image data, which is data of the image read by the reading unit, in a control unit. The method includes: a step of changing the resolution of the image data generated by the control unit by lowering the resolution of the image read by the reading unit; a step of causing the conveyance unit to convey the document at a first conveyance speed and generating, in the control unit, image data of an image having a first resolution when specific setting information, which is information indicating that slow conveyance of the document is required by the user, is not input to the control unit; a step of causing the conveyance unit to convey the document at a second conveyance speed, which is lower than the first conveyance speed, and generating, in the control unit, image data of an image having the first resolution when the specific setting information is input; a step of causing the conveyance unit to convey the document at a third conveyance speed, which is lower than the first conveyance speed, and generating, in the control unit, image data of an image having a second resolution, which is higher than the first resolution, when the specific setting information is not input; and a step of causing the conveyance unit to convey the document at the third conveyance speed and generating, in the control unit, image data of an image having the second resolution when the specific setting information is input.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0030] (First Embodiment) Hereinafter, a first embodiment in which the image reading apparatus is embodied will be described with reference to FIGS. 1 to 5. As shown in FIG. 1, the image reading apparatus 11 of the present embodiment includes a housing 12 and a cover member 13 rotatably supported by the housing 12. A user interface 50 of the apparatus is provided on the cover member 13. That is, the user interface 50 has a plurality of buttons 51 and a plurality of lamps 52.

[0031] One of the buttons 51 is a specific button 51A that is operated when instructing the implementation of image reading in the second reading mode described later. Also, one of the lamps 52 is a specific lamp 52A that is lit when the specific button 51A is in the on state. Note that the specific lamp 52A is turned off when the specific button 51A is in the off state.

[0032] Also, as shown in FIG. 2, the image reading apparatus 11 is provided with a set unit 14 on which an original MS for which image reading has not yet been performed is set. When a plurality of originals MS are set on the set unit 14, the originals MS are stacked on the set unit 14. Inside the housing 12, a conveyance device 20 as a conveyance unit for conveying the original MS and a reading device 30 for reading the image of the original MS conveyed by the conveyance device 20 are provided. Then, the original MS set on the set unit 14 enters the housing 12 one by one and is conveyed along a predetermined conveyance path. While being conveyed, the image of the original MS is read, and the original MS for which the image reading has been completed is discharged outside the housing 12.

[0033] As shown in FIG. 2, the conveying device 20 includes a feeding roller 21, a pair of discharging rollers 22, a pair of conveying rollers 23, and a pair of discharging rollers 24, which are arranged in order from upstream to downstream in the conveying direction of the document MS. Further, the conveying device 20 includes a feeding motor 25 and a conveying motor 26 as driving sources for conveying the document MS. The driving force from the feeding motor 25 is transmitted to the feeding roller 21, and the driving force from the conveying motor 26 is transmitted to the pair of discharging rollers 22, the pair of conveying rollers 23, and the pair of discharging rollers 24.

[0034] The feeding roller 21 feeds the lowermost document MS among the plurality of documents MS set in the setting unit 14 into the housing 12. Further, a guide member 27 is arranged above the feeding roller 21. The guide member 27 restricts the entry of documents other than the lowermost document MS into the housing 12.

[0035] The pair of discharging rollers 22 has a driving roller 221 drivingly connected to the conveying motor 26 and a driven roller 222 to which the driving force from the conveying motor 26 is transmitted through the driving roller 221. When the driving roller 221 and the driven roller 222 rotate, the document MS is sandwiched between the two rollers 221 and 222, and the document MS is sent out toward the pair of conveying rollers 23.

[0036] The driven roller 222 of the pair of discharging rollers 22 is a retard roller to which a constant rotational load is applied by a torque limiting mechanism such as a torque limiter. Therefore, when a plurality of documents MS are fed into the housing 12 from the setting unit 14 in a stacked state, only one document MS is sent out downstream in the conveying direction by the pair of discharging rollers 22. In this regard, the two rollers 221 and 222 constituting the pair of discharging rollers 22 function as "discharging rollers" for sending the document MS toward the pair of conveying rollers 23.

[0037] The pair of conveying rollers 23 is arranged upstream in the conveying direction on the right side in the drawing from the reading device 30. Such a pair of conveying rollers 23 has a driving roller 231 that is drivingly connected to the conveying motor 26, and a driven roller 232 to which the driving force from the conveying motor 26 is transmitted through the driving roller 231. Then, when the driving roller 231 and the driven roller 232 rotate, the original document MS is clamped by both rollers 231 and 232, and the original document MS is conveyed toward the reading device 30.

[0038] The pair of discharging rollers 24 is arranged downstream in the conveying direction on the left side in the drawing from the reading device 30. Such a pair of discharging rollers 24 has a driving roller 241 that is drivingly connected to the conveying motor 26, and a driven roller 242 to which the driving force from the conveying motor 26 is transmitted through the driving roller 241. Then, when the driving roller 241 and the driven roller 242 rotate, the original document MS is clamped by both rollers 241 and 242, and the original document MS is discharged outside the housing 12.

[0039] The reading device 30 has two reading units 31 and 32 arranged on the upper and lower sides sandwiching the original document MS conveyed along the conveying path. Among each of the reading units 31 and 32, the reading unit located on the lower side is the first reading unit 31, and the reading unit located on the upper side is the second reading unit 32. That is, the first reading unit 31 reads an image of one side (the lower surface in the drawing) of the original document MS, and the second reading unit 32 reads an image of the other side (the upper surface in the drawing) of the original document MS. Incidentally, as the reading unit, for example, a contact image sensor module (CISM) can be mentioned. Of course, other modules other than CISM may be adopted as the reading unit.

[0040] Incidentally, as shown in FIG. 2, an end detection sensor 600 for detecting the end of the original document MS is provided between the reading device 30 and the pair of conveying rollers 23 in the conveying direction of the original document MS. Also, between the delivery roller pair 22 and the conveyance roller pair 23 in the conveyance direction of the document MS, a double-feed detection sensor 610 for detecting that a plurality of documents MS are being conveyed in an overlapping state is provided. This double-feed detection sensor 610 is an acoustic wave sensor and has an output unit 611 that outputs acoustic waves and an input unit 612 into which the acoustic waves output from the output unit 611 are input. Then, one of the output unit 611 and the input unit 612 is arranged above the document MS conveyed along the conveyance path in the drawing, and the other of the output unit 611 and the input unit 612 is arranged below the document MS conveyed along the conveyance path in the drawing. In the example shown in FIG. 2, the input unit 612 is arranged above the drawing, and the output unit 611 is arranged below the drawing.

[0041] And the double-feed detection sensor 610 detects the attenuation rate α of the acoustic wave. When the output value of the acoustic wave output from the output unit 611 is “X1” and the input value of the acoustic wave input to the input unit 612 is “X2”, the attenuation rate α is a value that can be calculated using the following relational expression (Expression 1).

[0042] α = (X1 - X2) / X1 ···(Expression 1) By the way, in the image reading apparatus 11 of the present embodiment, the resolution of the image based on the image data output from the apparatus can be selected by the user. That is, the first reading mode, which is an example of the image reading mode, can be selected by an operation of the user interface 50 by the user or an operation by the user of an external device communicating with the image reading apparatus 11.

[0043] Further, in the image reading apparatus 11 that causes the reading units 31 and 32 to read the image of the conveyed document MS, the slower the conveyance speed of the document MS, the more image data with a higher resolution is generated. Therefore, it can also be said that the first reading mode for providing the user with image data with a high resolution is a mode in which the document MS is conveyed at a speed correlated with the resolution requested by the user.

[0044] FIG. 3 shows an example of a table indicating a plurality (here, three) of first reading modes. As shown in FIG. 3, the first mode is a reading mode that generates image data of an image with a high conveyance speed of the document MS and a low resolution. The second mode is a reading mode that generates image data of an image with a medium conveyance speed of the document MS and a medium resolution. The third mode is a reading mode that generates image data of an image with a low conveyance speed of the document MS and a high resolution.

[0045] And when the user instructs the image reading apparatus 11 to read an image, the user can select one reading mode (that is, the first reading mode) from among the above three modes.

[0046] Here, in the image reading apparatus 11 of the present embodiment, it is possible to read images of various documents MS having different thicknesses. And the thinner the thickness of the document MS, the more likely it is that conveyance failures such as paper jams will occur during conveyance. In order to suppress the occurrence of such conveyance failures, it is desirable to convey the document MS at a low speed.

[0047] Therefore, as described above, the user interface 50 is provided with a specific button 51A. This specific button 51A is a button that is turned on when reading an image of a document MS that is likely to have a conveyance failure during conveyance, such as a document MS with a thin thickness. And when the specific button 51A is turned on by the user's operation, specific setting information, which is information regarding a specific user operation, is input to the control device 60 as the control unit of the image reading apparatus 11 (see FIG. 4), and a second reading mode different from the first reading mode is implemented. Here, the "specific user operation" refers to the user's button operation for turning on the specific button 51A.

[0048] That is, when specific setting information is not input to the control device 60, the operation of reading an image from the document MS is set to the first reading mode. Also, when specific setting information is input to the control device 60, the operation of reading an image from the document MS is set to the second reading mode.

[0049] The second reading mode is a mode for generating image data with the same resolution as in the case of the first reading mode while transporting the document MS at a lower speed than in the case of the first reading mode. For example, when the user selects to execute the first mode, that is, when the resolution required by the user is low, and the specific button 51A is turned on, the second reading mode shown below is executed. · Transport the document MS at a lower speed than when executing the first mode. For example, transport it at the transport speed of the document MS in the case of the third mode, or at a speed equivalent to the transport speed. · Generate image data with the same resolution as in the case of the first mode.

[0050] Also, when the user selects to execute the third mode, that is, when the resolution required by the user is high, and the specific button 51A is turned on, the second reading mode shown below is executed. · Transport the document MS at a lower speed than when executing the third mode. · Generate image data with the same resolution as in the case of the third mode.

[0051] When such a second reading mode is executed, since the document MS is transported at a low speed, the occurrence of conveyance failure of the thin document MS is suppressed even when reading the image of the thin document MS. Moreover, even when the document MS is transported at a low speed in this way, the resolution of the image based on the generated image data is the same as the resolution required by the user, that is, the same resolution as in the case of the first reading mode selected by the user.

[0052] Next, referring to FIG. 4, the control device 60 of the image reading apparatus 11 will be described. The control device 60 includes a microcomputer composed of a CPU, ROM, RAM, etc., and various driver circuits. As shown in FIG. 4, such a control device 60 includes a conveyance control unit 61, a mode selection unit 66, a data generation unit 64, and a data output unit 65 as functional units constituted by at least one of software and hardware.

[0053] The conveyance control unit 61 controls the conveyance device 20. That is, when an instruction to start conveying the original MS, that is, an instruction to read the image of the original MS, is input, the conveyance control unit 61 drives the delivery motor 25 to rotate the feed roller 21. As a result, one original MS is fed into the housing 12 from the setting unit 14. Then, when the original MS conveyed by the rotation of the feed roller 21 is clamped by the two rollers 221 and 222 constituting the delivery roller pair 22, the conveyance control unit 61 stops driving the delivery motor 25.

[0054] Also, the conveyance control unit 61 drives the conveyance motor 26 to rotate the rollers 221, 231, 241, 222, 232, 242 of the delivery roller pair 22, the conveyance roller pair 23, and the discharge roller pair 24. Note that the timing of starting the drive of the conveyance motor 26 may be the same as the timing of starting the drive of the delivery motor 25, or may be after the timing of starting the drive of the delivery motor 25. Then, the conveyance control unit 61 stops driving the conveyance motor 26 after the timing when the rear end of the original MS has passed through the discharge roller pair 24.

[0055] Note that information regarding the conveyance speed of the original MS is input to the conveyance control unit 61 from the mode selection unit 66. Then, the conveyance control unit 61 controls the drive of the conveyance motor 26 so as to convey the original MS at a speed based on the input information.

[0056] The mode selection unit 66 determines the reading mode to be implemented based on the user information input when reading an image. That is, when information for specifying the resolution of the image is input from the user interface 50 or an external device, the mode selection unit 66 selects a first reading mode according to the resolution of the image requested by the user (see Fig. 3). For example, when the user requests a high-resolution image, the mode selection unit 66 selects the third mode. Then, the mode selection unit 66 outputs information regarding the selected reading mode to the transport control unit 61 and the data generation unit 64. Also, when the specific button 51A is in the on state, the mode selection unit 66 selects the second reading mode and outputs information regarding the reading mode to the transport control unit 61 and the data generation unit 64.

[0057] The data generation unit 64 controls each reading unit 31, 32 of the reading device 30 and acquires the images read by each reading unit 31, 32. Then, the data generation unit 64 generates image data that is the data of the images read by the reading units 31, 32 and outputs this image data to the data output unit 65.

[0058] The resolution of the image based on the image data generated at this time is the resolution according to the information regarding the resolution input from the mode selection unit 66. That is, when the specific button 51A is in the off state, the data generation unit 64 generates data of an image with a resolution according to the conveyance speed of the document MS. On the other hand, when the specific button 51A is in the on state, the data generation unit 64 generates data of an image with the resolution requested by the user even if the conveyance speed of the document MS is low.

[0059] Here, the acquisition of an image from the document MS is realized by causing the reading units 31 and 32 to read an image at every predetermined timing while the document MS is being conveyed. Therefore, the resolution of the image acquired by the reading units 31 and 32 becomes higher as the conveyance speed of the document MS becomes lower. Therefore, the resolution of the image acquired during the execution of the second reading mode may be higher than the resolution desired by the user. Thus, in the second reading mode, the data generation unit 64 lowers the resolution of the acquired image to the resolution desired by the user and generates image data of the same resolution.

[0060] Also, during the execution of the second reading mode, the data generation unit 64 may control the reading units 31 and 32 so as to be able to acquire an image with a low resolution (that is, an image with a resolution assuming that the first reading mode has been executed). For example, by delaying the above-described predetermined timing, it is possible to realize the acquisition of an image with a resolution lower than the resolution according to the conveyance speed of the document MS. In this case, the data generation unit 64 can generate image data of the resolution requested by the user even if the conveyance speed of the document MS is low. That is, it becomes unnecessary to perform the process of lowering the resolution of the acquired image.

[0061] The data output unit 65 transmits the image data generated by the data generation unit 64 to an external device. Next, with reference to the flowchart shown in FIG. 5, the processing procedure when reading an image of the document MS will be described.

[0062] As shown in FIG. 5, under the situation where any one of the first mode, the second mode, and the third mode is selected, it is determined whether the specific button 51A is in the ON state (step S11). When the specific button 51A is in the OFF state (step S11: NO), the first reading mode is selected (step S12), and the process proceeds to step S14 described later. On the other hand, when the specific button 51A is in the ON state (step S11: YES), the second reading mode is selected (step S13), the specific lamp 52A is turned on, and the process proceeds to the next step S14.

[0063] In step S14, by starting the implementation of the selected reading mode, the reading of the image is started. For example, when the specific button 51A is in the OFF state and the second mode is selected, the document MS is conveyed at a medium speed by the conveying device 20, and image data with a medium resolution is generated. Also, when the specific button 51A is in the ON state and the second mode is selected, the document MS is conveyed at a low speed by the conveying device 20, and image data of an image with a medium resolution is generated.

[0064] Then, while the image is being read in this way, it is determined whether the attenuation rate α detected by the double-feed detection sensor 610 is equal to or greater than the double-feed detection attenuation rate αTh1 (step S15). The double-feed detection attenuation rate αTh1 is a threshold value for determining whether a plurality of documents MS are being conveyed in an overlapping state. For example, assuming that only one document MS of normal thickness is being conveyed and the attenuation rate α when this document MS is located between the output unit 611 and the input unit 612 of the double-feed detection sensor 610 is defined as the "standard attenuation rate". In this case, the double-feed detection attenuation rate αTh1 is set to a value greater than the standard attenuation rate.

[0065] When the attenuation rate α is equal to or greater than the retransmission detection attenuation rate αTh1 (step S15: YES), it can be determined that the plurality of original manuscripts MS are being conveyed in an overlapping state, so the reading of the image is stopped (step S16). In this case, the conveyance of the original manuscript MS is stopped, and an error is notified to the user by the user interface 50. Then, this process ends.

[0066] On the other hand, when the attenuation rate α is less than the retransmission detection attenuation rate αTh1 (step S15: NO), it can be determined that only one original manuscript MS is being conveyed, so the reading of the image continues. Then, it is determined whether the reading of the image is completed (step S17).

[0067] Note that the trailing edge of the original manuscript MS can be detected based on the reading results of the reading units 31 and 32. That is, based on the reading results of the reading units 31 and 32, it can be determined whether the trailing edge of the original manuscript MS has come to be located downstream in the conveyance direction from the reading units 31 and 32. And when the trailing edge of the original manuscript MS has come to be located downstream in the conveyance direction from the reading units 31 and 32, it can be determined that the reading of the image of the original manuscript MS is completed.

[0068] When the reading of the image of the original manuscript MS has not been completed yet (step S17: NO), the process proceeds to step S15 described above, and the reading of the image continues. On the other hand, when the reading of the image of the original manuscript MS is completed (step S17: YES), the process proceeds to the next step S18.

[0069] In step S18, it is determined whether there is a next original manuscript MS for which the image is to be read. When there is a next original manuscript MS (step S18: YES), the process proceeds to step S14 described above, and the conveyance of the next original manuscript MS is started. In this case, the conveyance speed of the next original manuscript MS is the same as the conveyance speed of the previous original manuscript MS. On the other hand, when there is no next original manuscript MS (step S18: NO), the image data generated by the data generation unit 64 is output by the data output unit 65 (step S19), and this process ends.

[0070] In addition, when continuously reading images of a plurality of original manuscripts MS, the specific button 51A may be operated by the user during the continuous reading of a series of images. In the image reading apparatus 11 of the present embodiment, such an operation of the specific button 51A by the user is invalidated. That is, even if the specific button 51A is operated during the continuous reading of images, the conveyance speed of one original manuscript and the conveyance speed of the next original manuscript after the one original manuscript are made equal. In other words, the operation of the specific button 51A is valid until before the start of the continuous reading of a series of images, that is, until before the process described with reference to FIG. 5 is started.

[0071] As described above, according to the image reading apparatus 11 of the present embodiment, the following effects can be obtained. (1) When reading of an image is instructed under the situation where the specific button 51A is in the off state, the first reading mode is executed. That is, when the user recognizes that the thickness of the original manuscript MS set in the setting unit 14 is not thin, the reading of the image is instructed to the image reading apparatus 11 by the user without turning on the specific button 51A. At this time, the resolution of the image based on the generated image data can be selected by the user when the user inputs an instruction for reading. Therefore, the original manuscript MS is conveyed at a conveyance speed corresponding to the resolution of the image requested by the user, and image data of the resolution requested by the user is generated. Accordingly, image data of the resolution desired by the user can be provided to the user.

[0072] On the other hand, when image reading is instructed in a situation where the specific button 51A is in the ON state, the second reading mode is implemented. That is, when the user recognizes that the thickness of the document MS set in the setting unit 14 is thin, after the specific button 51A is turned on, the user instructs the image reading apparatus 11 to read an image. At this time, although the document MS is conveyed at a lower speed than in the case of the first reading mode, image data with the same resolution as in the case of the first reading mode is generated. That is, it is possible to provide the user with image data that does not depend on the conveyance speed of the document MS while suppressing conveyance failures such as paper jams. Therefore, even when the conveyance speed of the document MS is variable, it is possible to generate image data with the resolution desired by the user.

[0073] (Second Embodiment) Next, a second embodiment in which the image reading apparatus 11 is embodied will be described with reference to FIG. 6. In the second embodiment, a part of the processing procedure when the specific button 51A is in the ON state is different from that in the first embodiment. Therefore, in the following description, mainly the parts different from the first embodiment will be described, and the same reference numerals will be given to the same member configurations as in the first embodiment, and redundant descriptions will be omitted.

[0074] FIG. 6 shows a flowchart for explaining the processing procedure when reading an image of the document MS. As shown in FIG. 6, in a situation where any one of the first mode, the second mode, and the third mode is selected, it is determined whether the specific button 51A is in the ON state (step S11). When the specific button 51A is in the OFF state (step S11: NO), the first reading mode is selected (step S12), and the process proceeds to step S14 described later. On the other hand, when the specific button 51A is in the ON state (step S11: YES), the second reading mode is selected (step S13), and the process proceeds to the next step S14.

[0075] In step S14, by starting the execution of the selected reading mode, the reading of the image is started. Then, while the image is being read in this way, when the attenuation rate α detected by the double-feed detection sensor 610 becomes equal to or higher than the double-feed detection attenuation rate αTh1 (step S15: YES), it can be determined that the plurality of original manuscripts MS are being conveyed in an overlapping state, so the reading of the image is stopped (step S16). In this case, the conveyance of the original manuscript MS is stopped, and an error is notified to the user by the user interface 50. For example, the specific lamp 52A is lit. Then, this process ends.

[0076] On the other hand, when the attenuation rate α is less than the double-feed detection attenuation rate αTh1 (step S15: NO), it can be determined that only one original manuscript MS is being conveyed, so the reading of the image is continued. And when the reading of the image of the original manuscript MS has not been completed yet (step S17: NO), the process proceeds to step S15 described above, and the reading of the image of the original manuscript MS is continued. On the other hand, when the reading of the image of the original manuscript MS has already been completed (step S17: YES), the process proceeds to the next step S18.

[0077] In step S18, it is determined whether there is a next original manuscript MS for which the image is to be read. When there is no next original manuscript MS (step S18: NO), the image data generated by the data generation unit 64 is output by the data output unit 65 (step S19), and this process ends.

[0078] On the other hand, when there is a next original manuscript MS (step S18: YES), the process proceeds to step S11 described above, and the conveyance of the next original manuscript MS is started. That is, when the specific button 51A is changed during the reading of the previous image, although the conveyance speed of the original manuscript MS is changed from the time of reading the current image, the resolution of the image based on the generated image mode is the same as that at the time of reading the previous image.

[0079] For example, when the specific button 51A is shifted from the off state to the on state during the reading of the previous image, the first reading mode was implemented during the reading of the previous image, whereas the second reading mode is implemented during the reading of the current image. That is, at the start of the reading of the current image, the mode to be implemented is switched from the first reading mode to the second reading mode.

[0080] On the other hand, when the specific button 51A is shifted from the on state to the off state during the reading of the previous image, the second reading mode was implemented during the reading of the previous image, whereas the first reading mode is implemented during the reading of the current image. That is, when setting information indicating the end of the second reading mode is input while the second reading mode is selected, at the start of the reading of the current image, the mode to be implemented is switched from the second reading mode to the first reading mode. Therefore, in the image reading apparatus 11 of the present embodiment, the shift of the specific button 51A from the on state to the off state by the operation of the specific button 51A by the user corresponds to the "predetermined end condition".

[0081] As described above, according to the image reading apparatus 11 of the present embodiment, in addition to the effect (1) equivalent to that in the first embodiment described above, the following effects can be further obtained. (2) When continuously reading images of a plurality of originals MS, if the specific button 51A is turned on while one of the originals MS is being conveyed, the implementation of the first reading mode continues until the reading of the image of the one original is completed. That is, during the conveyance of one original, the reading mode is not changed, and the conveyance speed of the same original is not changed. Therefore, an increase in the control load due to the switching of the reading mode during the reading of the image can be suppressed.

[0082] After that, when reading the image of the next document, the second reading mode is implemented instead of the first reading mode. That is, when reading the image of a document after a certain document, the document is conveyed at a low speed. Moreover, since it is the second reading mode, even if the document is conveyed at a low speed, image data with the same resolution as in the case of the first reading mode is generated. Therefore, when reading the image of a document after the certain document, by conveying the document MS at a low speed, it is possible to suppress the occurrence of conveyance failure of the document MS while providing the user with image data that does not depend on the conveyance speed.

[0083] (3) However, when the specific button 51A is shifted from the on state to the off state while the image of the document MS is being read in the second reading mode, it can be determined that the end condition for implementing the second reading mode is satisfied. Therefore, when reading the image of the next document MS, the first reading mode will be implemented, and the document MS will be conveyed at the speed defined by the first reading mode. Thus, when the implementation of the second reading mode becomes unnecessary, it is possible to appropriately switch from the second reading mode to the first reading mode.

[0084] (Third Embodiment) Next, a third embodiment in which the image reading apparatus 11 is embodied will be described with reference to FIGS. 7 and 8. In the third embodiment, the difference from the first and second embodiments is that the thickness of the document MS to be read is automatically detected, and based on the detection result, it is determined whether to implement the second reading mode or the first reading mode. Therefore, in the following description, mainly the parts different from the first and second embodiments will be described, and the same member configurations as in the first and second embodiments will be denoted by the same reference numerals and redundant descriptions will be omitted.

[0085] Referring to FIG. 7, the control device 60 of the image reading apparatus 11 will be described. The control device 60 includes a microcomputer composed of a CPU, a ROM, a RAM, etc., and various driver circuits. As shown in FIG. 7, such a control device 60 includes a conveyance control unit 61, a mode selection unit 66, a data generation unit 64, and a data output unit 65 as functional units constituted by at least one of software and hardware.

[0086] The mode selection unit 66 determines whether the thickness of the conveyed original document MS is thin based on the attenuation rate α detected by the double-feed detection sensor 610. When it is determined that the thickness of the original document MS is not thin, the mode selection unit 66 selects a first reading mode (see FIG. 3) corresponding to the resolution of the image requested by the user, and outputs information regarding the selected first reading mode (for example, the third mode) to the conveyance control unit 61 and the data generation unit 64. On the other hand, when it is determined that the thickness of the original document MS is thin, the mode selection unit 66 selects a second reading mode, and outputs information regarding the selected second reading mode to the conveyance control unit 61 and the data generation unit 64.

[0087] Here, an example of a method for determining whether the thickness of the conveyed original document MS is thin will be described. That is, when the original document MS is positioned between the output unit 611 and the input unit 612 of the double-feed detection sensor 610, the sound wave output from the output unit 611 passes through the original document MS and is input to the input unit 612. At this time, when the sound wave transmits through the original document MS, the thinner the original document MS, the less the sound wave is attenuated. That is, based on the attenuation rate α of the sound wave, the thickness of the original document MS can be estimated to some extent. Therefore, a determination attenuation rate αTh2 is provided as a criterion for determining whether the thickness of the original document MS is thin, and when the attenuation rate α is less than the determination attenuation rate αTh2, it is determined that the thickness of the conveyed original document MS is thin.

[0088] Note that a plurality of thin original manuscripts MS may be conveyed in an overlapping state. For example, when two original manuscripts MS overlap, the attenuation rate α detected by the double-feed detection sensor 610 becomes larger than the attenuation rate when one original manuscript MS with a normal thickness is being conveyed. Therefore, the double-feed detection attenuation rate αTh1 is set to a value larger than the attenuation rate when one original manuscript MS with a normal thickness is being conveyed. Thereby, when the attenuation rate α is equal to or greater than the determination attenuation rate αTh2 and less than the double-feed detection attenuation rate αTh1, it can be determined that the thickness of the original manuscript MS being conveyed is not thin. On the other hand, when the attenuation rate α is equal to or greater than the double-feed detection attenuation rate αTh1, it can be determined that a plurality of original manuscripts MS are being conveyed in an overlapping state.

[0089] Next, with reference to the flowchart shown in FIG. 8, the processing procedure when reading an image of the original manuscript MS will be described. As shown in FIG. 8, the conveyance of the original manuscript MS in the first reading mode corresponding to the resolution of the image requested by the user is started (step S31). Then, when the original manuscript MS comes to be positioned between the output unit 611 and the input unit 612 of the double-feed detection sensor 610, it is determined whether the attenuation rate α detected by the double-feed detection sensor 610 is less than the determination attenuation rate αTh2 (step S32). That is, in step S32, it is determined whether the thickness of the original manuscript MS being conveyed is thin.

[0090] And when the attenuation rate α is less than the determination attenuation rate αTh2 (step S32: YES), it is determined that a thin original manuscript MS is being conveyed, and the reading mode is switched from the first reading mode to the second reading mode (step S33). Thereby, the conveyance speed of the original manuscript MS is reduced. When the second reading mode comes to be implemented in this way, the specific-use lamp 52A is lit. Then, the process proceeds to the next step S34.

[0091] In step S34, it is determined whether the leading edge of the document MS has been detected by the edge detection sensor 600. If the leading edge of the document MS has not been detected yet (step S34: NO), the process proceeds to step S32 described above. On the other hand, if the leading edge of the document MS has been detected (step S34: YES), the process proceeds to step S37 described later. That is, when the leading edge of the document MS passes through the edge detection sensor 600 and reaches immediately in front of the reading device 30, the change of the reading mode is prohibited and the conveyance speed of the document MS is not changed.

[0092] On the other hand, in step S32, when the attenuation rate α is equal to or greater than the determination attenuation rate αTh2 (NO), it can be determined that the thickness of the conveyed document MS is not thin. Therefore, it is determined whether the attenuation rate α is less than the double-feed detection attenuation rate αTh1 (step S35). In this step S35, it is determined whether a plurality of documents MS are being conveyed in an overlapping state. When the attenuation rate α is less than the double-feed detection attenuation rate αTh1 (step S35: YES), it can be determined that one document MS with a non-thin thickness is being conveyed, and thus the process proceeds to step S34 described above. In this case, while the document MS is being conveyed at the conveyance speed defined in the first reading mode, the images are read by the reading units 31 and 32. Note that when the document MS is being conveyed in the first reading mode in this way, the specific-use lamp 52A is turned off.

[0093] On the other hand, when the attenuation rate α is equal to or greater than the double-feed detection attenuation rate αTh1 (step S35: NO), it can be determined that a plurality of documents MS are being conveyed in an overlapping state, and thus the reading of the image is stopped (step S36). In this case, the conveyance of the document MS is stopped, and an error is notified to the user by the user interface 50. Then, this process is terminated.

[0094] In step S37, reading of the image of the conveyed document MS is started. Then, while the image is being read in this way, it is determined whether or not the attenuation rate α detected by the double-feed detection sensor 610 is less than the double-feed detection attenuation rate αTh1 (step S38). If the attenuation rate α is greater than or equal to the double-feed detection attenuation rate αTh1 (step S38: NO), since it can be determined that the plurality of documents MS are being conveyed in an overlapping state, the process proceeds to step S36 described above. That is, when it is detected that the plurality of documents MS are being conveyed in an overlapping state, the ongoing image reading is aborted.

[0095] On the other hand, if the attenuation rate α is less than the double-feed detection attenuation rate αTh1 (step S38: YES), it is determined whether or not the reading of the image of the conveyed document MS has been completed (step S39). If the image reading has not been completed yet (step S39: NO), the process proceeds to step S38 described above, and the image reading is continued. On the other hand, if the image reading has been completed (step S39: YES), the process proceeds to the next step S40.

[0096] In step S40, it is determined whether or not there is a next document MS for which image reading is to be performed. If there is a next document MS (step S40: YES), the process proceeds to step S31 described above, and conveyance of the next document MS is started. In this case, even after the image reading in the second reading mode has been performed, the conveyance of the document MS in the first reading mode is started. That is, the completion of the image reading of the document MS corresponds to a "predetermined end condition" for switching the mode from the second reading mode to the first reading mode.

[0097] On the other hand, if there is no next document MS (step S40: NO), the image data generated by the data generation unit 64 is output by the data output unit 65 (step S41), and this process ends.

[0098] As described above, according to the image reading apparatus 11 of the present embodiment, the following effects can be obtained. (4) When the thickness of the document MS being conveyed by the conveying device 20 is not thin, the first reading mode is implemented. When the user instructs the image reading device 11 to read the image of the document MS, the resolution of the image based on the generated image data can be selected by the user. Therefore, it is possible to provide the user with image data that is the data of an image with the resolution desired by the user.

[0099] On the other hand, when the thickness of the document MS being conveyed by the conveying device 20 is thin, the second reading mode is implemented. In this case, although the document MS is conveyed at a lower speed than in the case of the first reading mode, image data with the same resolution as in the case of the first reading mode is generated. That is, it is possible to provide the user with image data that does not depend on the conveyance speed of the document MS while suppressing conveyance failures such as paper jams. Therefore, even when the conveyance speed of the document MS is variable, it is possible to generate image data of an image with the resolution desired by the user.

[0100] (5) In the image reading device 11 of the present embodiment, when the attenuation rate α of the sound wave detected by the double-feed detection sensor 610 is less than the determination attenuation rate αTh2, it can be determined that the thickness of the conveyed document MS is thin, so the second reading mode is implemented. By using the detection result by the double-feed detection sensor 610 in this way, the second reading mode can be automatically selected and implemented.

[0101] (6) The double-feed detection attenuation rate αTh1, which is a threshold value for determining whether a plurality of documents MS are being conveyed in an overlapping state, is determined to be a value larger than the determination attenuation rate αTh2. By using this double-feed detection attenuation rate αTh1, it is possible to determine whether only one document with a non-thin thickness is being conveyed or a plurality of documents are being conveyed in an overlapping state. By adopting such a determination result, the image reading device 11 can be appropriately driven according to the situation.

[0102] (7) Note that the double-feed detection sensor 610 is disposed between the pair of conveyance rollers 23 and the pair of delivery rollers 22 in the conveyance direction. Therefore, before the leading edge of the document MS reaches the position of the reading device 30, it is possible to determine whether the thickness of the conveyed document MS is thin. Therefore, before the image reading by the reading units 31 and 32 is actually started, it is possible to determine whether to switch the mode from the first reading mode to the second reading mode or to continue the first reading mode. Accordingly, it is not necessary to change the conveyance speed of the document MS while the image is actually being read by the reading units 31 and 32.

[0103] (8) When the conveyance of the document MS in the second reading mode is completed, since the end condition of the second reading mode is satisfied, the conveyance of the document MS in the first reading mode is started. Therefore, when continuously reading images of a plurality of documents MS, if a part of each document MS is a thin document, the same document can be conveyed at a low speed only when reading the image of the thin document. Accordingly, even when reading an image of a document that is not thin, it is possible to suppress a decrease in the throughput of the image reading apparatus 11 as compared with the case where the document is conveyed at a low speed.

[0104] Note that each of the above embodiments may be modified as follows. ·In the third embodiment, if the double-feed detection sensor 610 is disposed upstream of the reading device 30 in the conveyance direction, the double-feed detection sensor 610 may be disposed at a position other than between the pair of delivery rollers 22 and the pair of conveyance rollers 23 in the conveyance direction. For example, the double-feed detection sensor 610 may be disposed between the reading device 30 and the pair of conveyance rollers 23 in the conveyance direction.

[0105] ·Any sensor other than the sound wave sensor may be applied as the double-feed detection sensor as long as it can detect whether the thickness of the conveyed document MS is thin and whether a plurality of documents MS are being conveyed in an overlapping state.

[0106] · When the original MS is being conveyed, the current value flowing through the conveyance motor 26 increases as the load applied to the roller pair that rotates with the conveyance motor 26 as the driving source increases. Such a load varies depending on the thickness of the original MS being conveyed and the number of overlapping original MSs. Therefore, in the second embodiment, instead of the attenuation rate α detected by the double-feed detection sensor 610, it may be determined whether the thickness of the original MS being conveyed is thin based on the current value flowing through the conveyance motor 26. Similarly, in each of the first and second embodiments, it may be determined whether a plurality of original MSs are being conveyed in an overlapped state based on the current value flowing through the conveyance motor 26.

[0107] · In each of the first and second embodiments, the user operation for selecting the second reading mode may be performed not by the user interface 50 of the image reading apparatus 11 but by an external apparatus capable of communicating with the image reading apparatus 11. In this case, when the control apparatus 60 of the image reading apparatus 11 receives specific setting information, which is information regarding the user operation, from the external apparatus, the second reading mode is to be implemented.

[0108] · In each of the first and second embodiments, when the reading of the image in the second reading mode is completed and the reading of the image based on the next job is to be performed, the specific button 51A may be turned off and the specific lamp 52A may be turned off, and the first reading mode may be implemented. In this case, the input of the image reading instruction based on the next job to the control apparatus 60 corresponds to the "end condition".

[0109] ·In each of the above embodiments, even when the third mode is selected by the user, the second reading mode is implemented as needed. However, this is not limiting, and the second reading mode may not be implemented when the third mode is selected. In this case, for example, in each of the first and second embodiments, when the third mode is selected, the third mode is implemented regardless of whether the specific button 51A is in the on state or the off state. Further, in the third embodiment, when the third mode is selected, the third mode is implemented even if the attenuation rate α of the sound wave detected by the retransmission detection sensor 610 is less than the determination attenuation rate αTh2.

[0110] ·In each of the first and second embodiments, even when the specific button 51A is in the on state, when the attenuation rate α of the sound wave detected by the retransmission detection sensor 610 is equal to or greater than the determination attenuation rate αTh2, the first reading mode may be implemented. Also, when the specific button 51A is in the on state and the attenuation rate α of the sound wave detected by the retransmission detection sensor 610 is less than the determination attenuation rate αTh2, the second reading mode may be implemented.

[0111] Further, when the specific button 51A is in the off state, even if the attenuation rate α of the sound wave detected by the retransmission detection sensor 610 is less than the determination attenuation rate αTh2, the first reading mode may be implemented.

[0112] ·The reading device 30 may be configured to include only one of the first reading unit 31 and the second reading unit 32. ·The conveying device 20 may be configured not to include the sending motor 25. In this case, the feed roller 21 may be rotated by driving the conveying motor 26.

[0113] ·If the image reading device is a device that generates image data related to the image of the document and outputs it to an external device, it may be embodied in other devices such as a facsimile device.

Explanation of Reference Numerals

[0114] 11… Image reading device, 20… Conveyor device as a conveyance unit, 221, 222… Rollers functioning as delivery rollers, 23… Pair of conveyance rollers, 31, 32… Reading units, 60… Control device as a control unit, 600… End detection sensor constituted by a sound wave sensor, MS… Manuscript, α… Attenuation rate, αTh1… Double-feed detection attenuation rate, αTh2… Judgment attenuation rate.

Claims

1. A conveying unit capable of conveying a document; an acoustic wave sensor that outputs an acoustic wave to the document being conveyed by the conveying unit and detects an attenuation rate of the acoustic wave; a reading unit that reads an image of the document conveyed by the conveying unit; a control unit that generates image data that is data of an image read by the reading unit, the reading unit is configured to read an image of the original document at a predetermined timing when the original document is being transported by the transport unit, the sonic wave sensor is a sensor capable of detecting whether a plurality of documents are being conveyed in a superimposed state based on an attenuation rate of a sonic wave; The control unit is capable of executing a first reading mode and a second reading mode, the control unit, in the first reading mode, causes the reading unit to read an image from the document conveyed by the conveying unit at a speed corresponding to a required resolution, and generates image data of the image read by the reading unit; the control unit, in the second reading mode, causes the reading unit to read an image from a document conveyed by the conveying unit at a speed slower than that in the first reading mode, while delaying the timing compared to that in the first reading mode, thereby generating image data of an image with the same resolution as that in the first reading mode; The control unit switches the reading mode from the first reading mode to the second reading mode based on an attenuation rate of the sound wave detected by the sound wave sensor after starting transport of the document in the first reading mode.

1. An image reading apparatus comprising:

2. A conveying unit capable of conveying a document; an acoustic wave sensor that outputs an acoustic wave to the document being conveyed by the conveying unit and detects an attenuation rate of the acoustic wave; a reading unit that reads an image of the document conveyed by the conveying unit; a control unit that generates image data that is data of an image read by the reading unit, the reading unit is configured to read an image of the original document at a predetermined timing when the original document is being transported by the transport unit, the sonic wave sensor is a sensor capable of detecting whether a plurality of documents are being conveyed in a superimposed state based on an attenuation rate of a sonic wave; The control unit is capable of executing a first reading mode and a second reading mode, the control unit, in the first reading mode, causes the reading unit to read an image from the document conveyed by the conveying unit at a speed corresponding to a required resolution, and generates image data of the image read by the reading unit; the control unit, in the second reading mode, causes the reading unit to read an image from the document transported by the transport unit at a speed slower than that in the first reading mode, while lowering a resolution of the image read by the reading unit to generate image data of an image with the same resolution as that in the first reading mode; The control unit switches the reading mode from the first reading mode to the second reading mode based on an attenuation rate of the sound wave detected by the sound wave sensor after starting transport of the document in the first reading mode.

1. An image reading apparatus comprising:

3. a threshold value for the attenuation rate of the sound wave detected by the sound wave sensor is set to a determination attenuation rate and a double feed detection attenuation rate that is greater than the determination attenuation rate; The control unit is When an attenuation rate of the sound waves detected by the sound wave sensor while the document is being transported by the transport unit is equal to or greater than the determination attenuation rate and is less than the double feed detection attenuation rate, the first reading mode is executed; When the attenuation rate of the sound waves detected by the sonic wave sensor is equal to or greater than the double feed detection attenuation rate while the document is being transported by the transport unit, the transport unit stops transporting the document and the reader stops reading the image.

3. The image reading apparatus according to claim 1, wherein the image reading apparatus is a digital camera.

4. An edge detection sensor is provided between the conveying unit and the reading unit in a conveying direction of the document, the edge detection sensor detecting an edge of the document; The control unit, after switching the reading mode from the first reading mode to the second reading mode, causes the reading unit to read an image from the document when the edge detection sensor detects an edge of the document.

3. The image reading apparatus according to claim 1, wherein the image reading apparatus is a digital camera.

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