Image reading apparatus and image reading method

Abstract

To provide an image reading apparatus capable of correctly determining the size of a medium even in an environment where external light enters.SOLUTION: Based on a difference between a first image obtained by scanning a part of a medium by a sensor module in a state where a light source is turned off when a top plate is being closed and a second image obtained by scanning a part of the medium by the sensor module in a state where the light source is turned on when the top plate is being closed, A first mode in which a size of the medium is determined, and a second mode in which the size of the medium is determined by performing edge detection on a third image obtained by scanning a part of the medium by the sensor module in a state where the light source is turned on when the top plate is closed, wherein the size of the medium is determined in the first mode when the intensity of the external light is within the predetermined range, and the size of the medium is determined in the second mode when the intensity of the external light is outside the predetermined range.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an image reading device and an image reading method. [Background technology]

[0002] Techniques for detecting the size of a document placed on a document table in image reading devices such as scanners are known. For example, Patent Document 1 discloses an image reading device that, when detecting the size, reduces the amount of light irradiated onto the document compared to normal scanning and illuminates it from one direction, thereby highlighting the shading of uneven surfaces of the document, thereby enabling accurate size detection even for thin documents that are less likely to produce shadows on the edges when light is irradiated. Patent Document 2 also discloses a document size detection device that, when the document pressure plate is closing, detects external light such as sunlight or room light incident on a photoelectric conversion element with the light source turned off, and then detects light incident on the photoelectric conversion element with the light source turned on, and determines the size of the document from points excluding the points of external light, thereby enabling accurate document size detection even in an environment where external light is incident on the document reading device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-100377 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-126132 Summary of the Invention [Problem to be solved by the invention]

[0004] As described in Patent Document 1 and Patent Document 2, various efforts have been made to date to develop technologies for determining the size of a document. However, when extremely strong external light is incident, there is a risk that the size of the document may be misjudged, and there is still room for improvement. [Means for solving the problem]

[0005] One aspect of the image reading device according to the present invention is a first mode for determining the size of the medium based on the difference between a first image obtained by a first scan in which the sensor module scans a portion of the medium with the light source turned off when the top panel is in the process of closing, and a second image obtained by a second scan in which the sensor module scans a portion of the medium with the light source turned on when the top panel is in the process of closing; a second mode in which the size of the medium is determined by performing edge detection on a third image obtained by a third scan in which the sensor module scans a portion of the medium while the light source is turned on when the top panel is closed; and and determining whether the intensity of external light is within a predetermined range; If the intensity of the external light is within the predetermined range, determining the size of the medium in the first mode; If the intensity of the external light is outside the predetermined range, the size of the medium is determined in the second mode.

[0006] One aspect of the image reading method according to the present invention is to determining whether the intensity of external light is within a predetermined range; If the intensity of the external light is within the predetermined range, the second light obtained by the first scan in which the sensor module scans a part of the medium with the light source turned off when the top panel is in the process of closing is detected. executes a first mode in which the size of the medium is determined based on a difference between the first image and a second image obtained by a second scan in which the sensor module scans a portion of the medium while the light source is turned on when the top panel is in the process of closing; If the intensity of the external light is outside the specified range, a second mode is executed in which the sensor module, with the light source turned on when the top panel is closed, performs edge detection on a third image obtained by a third scan in which the sensor module scans a portion of the medium, thereby determining the size of the medium. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is an external perspective view of the multifunction peripheral. [Figure 2] FIG. [Figure 3] FIG. 2 is a plan view showing the arrangement of an image reading surface and a document table. [Figure 4] FIG. 2 is a side cross-sectional view of the drive mechanism of the ADF. [Figure 5] FIG. 2 illustrates an example of a functional configuration of an image reading apparatus. [Figure 6] FIG. 2 is a plan view of the image reading device as seen in the −Z direction. [Figure 7] FIG. 2 is a side view of the image reading device as seen in the −Y direction. [Figure 8] FIG. 2 is a side view of the image reading device as seen in the −Y direction. [Figure 9] FIG. 2 is a side view of the image reading device as seen in the −Y direction. [Figure 10] FIG. 2 is a side view of the image reading device as seen in the −Y direction. [Figure 11] 10A and 10B are diagrams showing examples of a second image and a third image obtained when the image reading device is not exposed to external light. [Figure 12] 10A and 10B are diagrams showing examples of a second image and a third image obtained when external light is incident on the image reading device. [Figure 13] 10A and 10B are diagrams showing examples of a first image and a second image obtained when external light is incident on the image reading device; [Figure 14] 10A and 10B are diagrams showing examples of a first image and a second image obtained when strong external light is incident on the image reading device; [Figure 15] 10A and 10B are diagrams showing an example of the color tone of each pixel of a first image, the color tone of each pixel of a second image, the color tone of each pixel of a third image, and a determination result. [Figure 16] 10A and 10B are diagrams showing an example of the color tone of each pixel of a first image, the color tone of each pixel of a second image, the color tone of each pixel of a third image, and a determination result. [Figure 17]10A and 10B are diagrams showing an example of the color tone of each pixel of a first image, the color tone of each pixel of a second image, the color tone of each pixel of a third image, and a determination result. [Figure 18] 10A and 10B are diagrams showing an example of the color tone of each pixel of a first image, the color tone of each pixel of a second image, the color tone of each pixel of a third image, and a determination result. [Figure 19] FIG. 10 is a time chart illustrating an example of a time series of a process for returning the scanner board from a sleep state and a process for determining the size of a medium. [Figure 20] FIG. 10 is a time chart illustrating an example of a time series of a process for returning the scanner board from a sleep state and a process for determining the size of a medium. [Figure 21] FIG. 2 is a flowchart illustrating an example of a procedure of an image reading method according to the present embodiment. [Figure 22] FIG. 22 is a flowchart showing an example of the detailed procedure of step S20 in FIG. 21. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the present invention will be described below with reference to the drawings. The drawings used are for the convenience of explanation. Note that the embodiments described below do not unduly limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0009] The image reading device of the present invention may be, for example, a standalone scanner device or a scanner unit included in a multifunction peripheral. The image reading apparatus of this embodiment will be described using the image reading apparatus of the present invention as an example.

[0010] 1. Structure of the multifunction printer FIG. 1 is an external perspective view of a multifunction peripheral 10 equipped with an image reading device 1 according to this embodiment. The multifunction peripheral 10 includes a device main body 12 having a generally rectangular parallelepiped shape. The device main body 12 includes a recording device 13 that records on paper, and an image reading device 1 that is provided on the recording device 13 and generates an image by reading information such as pictures, text, and photographs formed on a medium P such as paper placed thereon. For example, an image generated by the image reading device 1 is printed on paper by the recording device 13. In the XYZ coordinate system, the X direction represents the height direction of the medium P placed on the image reading device 1, the Y direction represents the width direction of the medium P, and the Z direction represents the height direction of the image reading device 1. Hereinafter, the medium P on which information such as pictures, text, and photographs is formed will be referred to as a "document," and reading the information formed on the medium P will sometimes be referred to as "reading the document."

[0011] The image reading device 1 includes an automatic document feeder (ADF) 27. The ADF 27 is rotatable around a rotation axis J on the rear side of the device body 12, which is the -Y direction side, and also functions as a top panel that can be opened and closed relative to the top of the device body 12.

[0012] The ADF 27 includes a document transport unit 28 equipped with a drive mechanism for transporting a document, a document placement surface 40, and a document discharge surface 42. The document placed on the document placement surface 40 is fed into the image reading device 1 by the document transport unit 28, read, and then discharged and placed on the document discharge surface 42.

[0013] An operation unit 16 is provided at the top of the front side, which is in the +Y direction of the device main body 12, and is configured to include a power button, print setting buttons, a display panel, etc. for operating the multifunction device 10.

[0014] A rear tray 24 on which paper is placed is provided on the rear side, which is the -Y direction side, of the device main body 12. Paper placed on the rear tray 24 is fed to the recording device 13 and recorded on.

[0015] A paper storage section 26 for storing multiple sheets of paper is provided on the bottom side, which is the -Z direction side, of the front tray 22. The paper storage section 26 is provided at the bottom of the device main body 12 so as to be slidable in the Y direction, and is configured to be detachable from the device main body 12. Paper placed in the paper storage section 26 is fed to the recording device 13 and recorded on.

[0016] A drawer section 20 that is attached to a front tray 22 and is slidable in the Y direction is provided on the front side of the device body 12. Paper that has been fed from a rear tray 24 or a paper storage section 26 to the recording device 13 and recorded on is discharged from an opening 18 provided on the front side of the device body 12 and placed on the front tray 22 or the drawer section 20 that has been drawn out from the front tray 22.

[0017] 2. Structure of image reading device Next, a description will be given of the image reading device 1. Fig. 2 is a perspective view showing the ADF 27, Fig. 3 is a plan view showing the arrangement of the image reading surface 34 and the document table 36, and Fig. 4 is a side cross-sectional view of the drive mechanism of the ADF 27.

[0018] The image reading unit 30 in FIG. 4 includes a sensor module 32, an image reading surface 34, and a document table 36. The sensor module 32 is configured to be movable in the X direction by a drive mechanism (not shown). The sensor module 32 also includes a sensor element 32 for image reading that extends in the Y direction. It is equipped with an optical detector for

[0019] An image reading surface 34 and a document table 36 are arranged in parallel on the upper portion 12a of the device body 12 in FIG. 3 . The image reading surface 34 and the document table 36 are made of flat, transparent glass plates. Both ends of the document table 36 in the Y direction and the end on the +X direction side in the X direction are supported by a frame (not shown) provided within the device body 12. The image reading surface 34 is provided to face a portion of a document transport path 38 (described later) when the ADF 27 is closed relative to the upper portion of the device body 12 shown in FIG. 3 . The length of the image reading surface 34 in the Y direction is set to correspond to the width of the document. On the other hand, the length of the image reading surface 34 in the X direction is set shorter than the length in the document transport direction and the document table 36, so that when a portion of the document transported along the document transport path 38 comes into contact with the image reading surface 34, the sensor module 32 can read the portion of the document that comes into contact with the image reading surface 34. The sensor module 32 is capable of reading the document through the image reading surface 34 when the document comes into contact with the image reading surface 34 .

[0020] The lengths of the platen 36 in the X and Y directions are set according to the maximum size of a document that can be read by the device body 12. The platen 36 of the multifunction peripheral 10 of this embodiment is configured to position and place standard-sized documents such as A3 and A4 at a predetermined position. The document reading operation on the platen 36 is performed with the document placed on the platen 36. Specifically, with the ADF 27 open relative to the device body 12, the document is positioned and placed on the platen 36, and after the document is placed, the ADF 27 is closed again relative to the device body 12. The sensor module 32 is then moved in the X direction. This allows the sensor module 32 to read the document placed on the platen 36 via the platen 36.

[0021] 2 and 4, the document transport unit 28 of the ADF 27 will be described. The document transport unit 28 includes a document transport path 38 that extends from a document placement surface 40 to a document discharge surface 42. The document transport unit 28 is configured to transport a document placed on the document placement surface 40 along the document transport path 38 while curving and inverting the document, and discharge the document onto the document discharge surface 42.

[0022] The document transport unit 28 is provided with a cover 44 that covers at least a portion of the document transport path 38. The cover 44 can be in a state in which it covers a portion of the document transport path 38 for the document transport unit 28, or in a state in which it opens a portion of the document transport path 38. For the sake of explanation, Fig. 2 shows a state in which the cover 44 is removed from the document transport unit 28.

[0023] The document transport path 38 includes a plurality of rollers and a plurality of guide members arranged along the document transport path 38, and is capable of transporting documents from the document placement surface 40 to the document discharge surface 42. A feed roller 46 that is driven to rotate by a drive source (not shown) is provided on the -X direction side of the document placement surface 40. When the feed roller 46 comes into contact with the uppermost document among the plurality of documents placed on the document placement surface 40, the feed roller 46 feeds the uppermost document downstream of the document transport path 38.

[0024] In the document transport path 38, a separation roller 48, a first transport auxiliary roller 50, a first transport roller pair 52, a second transport auxiliary roller 54, and a second transport roller pair 56 are provided along the document transport direction downstream of the feed roller 46. The separation roller 48, the first transport roller pair 52, and the second transport roller pair 56 are configured to be supplied with a driving force from a drive source (not shown) and to be driven to rotate.

[0025] The document sent downstream in the conveying direction by the feed roller 46 passes through a separation roller 48, a first conveying auxiliary roller 50, a first conveying roller pair 52, a second conveying auxiliary roller 53, and a conveying path. The sheet is conveyed by the first conveying roller pair 54 and the second conveying roller pair 56 in that order, and reaches the image reading surface 34 .

[0026] The document transported to the image reading surface 34 is read by the sensor module 32 provided at a position opposite to the image reading surface 34. The document read by the sensor module 32 on the image reading surface 34 is transported in this order by a third transport roller pair 58 and a discharge roller pair 60 provided downstream of the image reading surface 34 on the transport path, and is discharged onto the document discharge surface 42. The third transport roller pair 58 and the discharge roller pair 60 are configured to be rotationally driven by a driving force supplied from a drive source (not shown).

[0027] The document pressing unit 62 includes a sheet-like member 64, an elastic member 66, a reinforcing member 68, and a fixing member 70a. The sheet-like member 64 is disposed on the side of the document pressing unit 62 that faces the document table 36, i.e., on the side closer to the document. In this embodiment, the sheet-like member 64 is made of polypropylene material with a thickness of 0.2 mm. The sheet-like member 64 is also formed to a size that corresponds to the document table 36.

[0028] An elastic member 66 is disposed on the +Z direction side of the sheet-like member 64. In this embodiment, the elastic member 66 is made of a sponge material with a thickness of 3 mm. The elastic member 66 is also formed to a size corresponding to the document table 36, that is, to the same size as the sheet-like member 64. The sheet-like member 64 and the elastic member 66 are bonded over their entire surfaces with an adhesive.

[0029] A plate-shaped reinforcing member 68 is disposed on the +Z direction side of the elastic member 66. In this embodiment, the reinforcing member 68 is made of a polycarbonate material with a thickness of 1 mm. The reinforcing member 68, like the sheet-like member 64 and the elastic member 66, is formed to a size corresponding to the document table 36. The reinforcing member 68 is attached to the elastic member 66 via adhesive tape (not shown) provided on both ends of the elastic member 66 on the Y direction side.

[0030] A fixing member 70a is disposed on the upper surface of the reinforcing member 68 on the +Z direction side. In this embodiment, the fixing member 70a is made of an elastic material such as sponge or urethane. The fixing member 70a has a rectangular parallelepiped shape with squares of the same size when viewed from the Z direction.

[0031] The upper surface of the fixed member 70a on the +Z direction side is attached via an adhesive tape (not shown) to an area facing the document table 36 below the ADF 27. The lower surface of the fixed member 70a on the -Z direction side is attached to the upper surface of the reinforcing member 68 via an adhesive tape (not shown).

[0032] 3. Functional configuration and operation of image reading device The functional configuration and operation of the image reading device 1 will be described below with reference to Figs. 5 to 10. Fig. 5 is a diagram showing an example of the functional configuration of the image reading device 1. Fig. 6 is a plan view of the image reading device 1 as seen in the -Z direction. Figs. 7 to 10 are side views of the image reading device 1 as seen in the -Y direction. Note that Figs. 6 to 10 show only the main components of the image reading device 1 in a simplified schematic manner.

[0033] 5, the image reading device 1 includes an operation unit 16, a sensor module 32, a photosensor 80, an open / close sensor 81, and a scanner board 100. The scanner board 100 has various circuits mounted thereon, including a control circuit 110, an image processing circuit 120, and an analog front end (AFE) 130.

[0034] As shown in Figures 5, 6 and 7, the sensor module 32 includes a first light source 321, a second light source 322 and an image reading sensor 323. As shown in Figures 6 and 7, the sensor module 32 may also include a first light guide 324, a second light guide 325 and a lens 326. The first light source 321 and the first light guide 324 are The first light source 321 is disposed at one end of the sensor module 32 in the X direction, and the second light source 322 and the second light guide 325 are disposed at the other end of the sensor module 32 in the X direction. The image reading sensor 323 and the lens 326 are disposed between the first light guide 324 and the second light guide 325. The length of the first light guide 324 in the Y direction is slightly longer than the length of the image reading sensor 323 in the Y direction, so that light emitted by the first light source 321 is guided in the +Y direction by the first light guide 324 and irradiated onto the medium P placed on the platen 36. Similarly, the length of the second light guide 325 in the Y direction is slightly longer than the length of the image reading sensor 323 in the Y direction, so that light emitted by the second light source 322 is guided in the -Y direction by the second light guide 325 and irradiated onto the medium P placed on the platen 36. The light irradiated onto the medium P is reflected by the medium P, and this reflected light is collected by a lens 326 and incident on an image reading sensor 323 .

[0035] The image reading device 1 causes the first light source 321 and the second light source 322 to emit light in response to a signal output from the scanner board 100, and causes the image reading sensor 323 to receive reflected light resulting from the emitted light. The image reading device 1 then generates an electrical signal in the sensor module 32 in response to the amount of reflected light, and generates an image data signal IMG including image data in response to the electrical signal in the scanner board 100. The image reading sensor 323 is, for example, a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor. In this way, the scanner board 100 is a board that controls the sensor module 32.

[0036] A read control signal SCS is input to the scanner board 100 when the user operates the operation unit 16. If the read control signal SCS input to the scanner board 100 is a signal to start reading the document, the control circuit 110 starts reading the document.

[0037] Specifically, the control circuit 110 outputs drive signals DrvR1, DrvG1, and DrvB1 to the red LED 321R, green LED 321G, and blue LED 321B of the first light source 321, respectively, and outputs drive signals DrvR2, DrvG2, and DrvB2 to the red LED 322R, green LED 322G, and blue LED 322B of the second light source 322, respectively.

[0038] In detail, the control circuit 110 first supplies drive signals DrvR1 and DrvR2 to the red LEDs 321R and 322R, respectively, for an exposure time Δt1 in a cycle T, thereby causing the red LEDs 321R and 322R to emit light simultaneously. Next, the control circuit 110 supplies drive signals DrvG1 and DrvG2 to the green LEDs 321G and 322G for an exposure time Δt2 in a cycle T, thereby causing the green LEDs 321G and 322G to emit light simultaneously. Next, the control circuit 110 supplies drive signals DrvB1 and DrvB2 to the blue LEDs 321B and 322B for an exposure time Δt3 in a cycle T, thereby causing the blue LEDs 321B and 322B to emit light simultaneously. In this case, the control circuit 110 outputs drive signals DrvR1, DrvG1, DrvB1, DrvR2, DrvG2, and DrvB2 so that the sum of the exposure times Δt1, Δt2, and Δt3 is shorter than the period T and so that the red LEDs 321R and 322R, the green LEDs 321G and 322G, and the blue LEDs 321B and 322B emit light exclusively.

[0039] The control circuit 110 also generates a clock signal CLK and a resolution setting signal RES for controlling the operation of the image reading sensor 323 and supplies them to the image reading sensor 323. The clock signal CLK is a signal that defines the operation timing of the image reading sensor 323, and the resolution setting signal RES is a signal that sets the resolution at which the image reading device 1 reads a document.

[0040] That is, the image reading sensor 323 generates an electrical signal corresponding to the information formed on the medium P at a resolution defined by the resolution setting signal RES in accordance with the timing of the clock signal CLK. For example, the resolution at which the image reading sensor 323 reads is determined by the resolution setting signal RES. It is set by the number of rising edges of the clock signal CLK during the active period.

[0041] Furthermore, the control circuit 110 generates a chip enable signal EN that becomes active for a certain period of time after causing the first light source 321 and the second light source 322 to emit light, and supplies the signal to the image reading sensor 323. The image reading sensor 323 generates an electrical signal according to the amount of reflected light received while the chip enable signal EN is active, and outputs the electrical signal as an image signal SO. Note that, hereinafter, the first light source 321 and the second light source 322 emitting light may be referred to as "turning on," and the first light source 321 and the second light source 322 not emitting light may be referred to as "turning off."

[0042] The image reading sensor 323 also has n light receiving elements (not shown). The n light receiving elements are arranged in a row along the Y direction. Each of the n light receiving elements detects the light reflected from the medium P, one line at a time, every period T. An electrical signal corresponding to the reflected light detected by each of the n light receiving elements is output to the scanner board 100 as an image signal SO.

[0043] That is, when the image reading sensor 323 detects reflected light for a total of m lines every cycle T as the medium P is transported, the image signal SO contains n electrical signals corresponding to the amount of reflected light detected by each of the n light receiving elements, serially for m lines. In other words, the image signal SO contains a total of n×m electrical signals serially.

[0044] In the following description, the electrical signals detected by the n light receiving elements are referred to as pixel information PS. That is, the image reading sensor 323 generates m sets of n pieces of pixel information PS as the medium P is transported, and outputs an image signal SO including the generated n × m pieces of pixel information PS in series to the scanner board 100.

[0045] The image signal SO output from the image reading sensor 323 is input to the analog front end 130. The analog front end 130 sequentially receives the image signals SO output from the image reading sensor 323 as the medium P is transported, and performs amplification and A / D conversion on the received image signals SO to generate an image information signal IS, which is a digital signal corresponding to the image signal SO. In other words, the image information signal IS is a signal obtained by converting the image signal SO, which includes n×m pieces of pixel information PS serially, into a digital signal, and the image information signal IS serially includes digital information corresponding to each of the n×m pieces of pixel information PS included in the image signal SO. The digital information corresponding to the n×m pieces of pixel information PS included in this image information signal IS is referred to as pixel information PSD.

[0046] The analog front end 130 outputs the image information signal IS to the image processing circuit 120. The image processing circuit 120 has a calculation unit 121 and a memory unit 122. The image information signal IS is stored in the memory unit 122. As a result, n×m pieces of pixel information PSD are stored in the memory unit 122. The calculation unit 121 reads out necessary information from the n×m pieces of pixel information PSD stored in the memory unit 122, and performs various processes, including correction and interpolation, on the read pixel information PSD to generate an image corresponding to the information formed on the medium P. The control circuit 110 then outputs the generated image to the recording device 13 as an image data signal IMG.

[0047] The control circuit 110 may store the generated image in the storage unit 122. In this case, the image stored in the storage unit 122 may be output to the recording device 13 as an image data signal IMG in response to a user request input via the operation unit 16 or the like.

[0048] In this way, the image reading device 1 can read the first light source 321 and the second light source 322 when the ADF 27 is closed. The ADF 27 has a normal scan mode in which the medium P is scanned by the sensor module 32 with the first light source 321 and the second light source 322 turned on, to read information formed on the medium P. The user opens the ADF 27, places the medium P on the platen 36, closes the ADF 27, and then operates the operation unit 16 to start reading the document in the normal scan mode. The open / close sensor 81, not shown in FIGS. 1 to 4, is a sensor that detects whether the ADF 27 is open or closed, and is capable of detecting at least three states: an open state in which the ADF 27 is fully open, a closed state in which the ADF 27 is completely closed, and a half-closed state in which the ADF 27 is in the process of closing.

[0049] Therefore, the control circuit 110 determines the open / closed state of the ADF 27 based on the signal output from the open / close sensor 81. When it determines that the ADF 27 has transitioned from a closed state to an open state, it performs preprocessing for reading the original. When the ADF 27 is closed, the sensor module 32 is located at the standby position HP shown in FIG. 6. As shown in FIG. 7, a white reference plate 90 is provided at the standby position HP. When the sensor module 32 is ready to operate, the control circuit 110 controls the sensor module 32 to turn on the first light source 321 and the second light source 322 to irradiate the white reference plate 90 with light, and the image reading sensor 323 detects the reflected light. The image processing circuit 120 then acquires an image information signal IS corresponding to the image signal SO output from the sensor module 32 and stores the digital value of this image information signal IS as a white reference value. Furthermore, the control circuit 110 turns off the first light source 321 and the second light source 322, and the image processing circuit 120 acquires an image information signal IS corresponding to the image signal SO output from the sensor module 32 and stores the digital value of this image information signal IS as a reference value for black. The reference values ​​for white and black are used by the image processing circuit 120 as data for shading correction when reading an image formed on the medium P.

[0050] Thereafter, the control circuit 110 determines the size of the medium P until the user performs an operation to start scanning the document. Specifically, the control circuit 110 determines the size of the medium P in the height direction (X direction) based on the output signal of at least one photosensor 80. Although the photosensor 80 is not shown in FIGS. 1 to 4, as shown in FIG. 6, it is disposed at a predetermined location on the −Z direction side of the document table 36, emits light in the +Z direction, and detects reflected light of the emitted light. Therefore, when the ADF 27 is in a semi-closed state, if a portion of the medium P placed on the document table 36 overlaps with the photosensor 80 in the Z direction, the photosensor 80 detects the reflected light and outputs a high-level signal. On the other hand, if the entire medium P does not overlap with the photosensor 80 in the Z direction, the photosensor 80 does not detect the reflected light and outputs a low-level signal. When the ADF 27 is in a half-closed state, external light (visible light) may be incident on the photosensor 80, so a sensor that emits and detects infrared light, for example, is used as the photosensor 80 so as not to detect visible light.

[0051] In FIG. 6, two photosensors 80a and 80b are provided, and when an A4-sized medium P is placed vertically on platen 36, neither photosensor 80a nor 80b detects reflected light. When an A4-sized medium P is placed horizontally on platen 36, photosensor 80a detects reflected light, but photosensor 80b does not. When an A3-sized medium P is placed horizontally on platen 36, both photosensors 80a and 80b detect reflected light. Therefore, control circuit 110 can determine the size of medium P in the height direction (X direction) based on the output signals of photosensors 80a and 80b.

[0052] When the ADF 27 is in the closed state, the sheet-like member 64 overlaps the photosensor 80 in the Z direction, and the photosensor 80 detects the reflected light. Therefore, the control circuit 110 acquires the output signal O1 of the photosensor 80 when the ADF 27 is in the half-closed state, and acquires the output signal O2 of the photosensor 80 when the ADF 27 is in the closed state. If the output signals O1 and O2 are both at a high level, a part of the medium P overlaps the photosensor 80, and the output If the signals O1 and O2 are at a low level and a high level, respectively, it can be determined that the medium P does not overlap the entire photosensor 80.

[0053] The control circuit 110 also uses the sensor module 32 to determine the size of the medium P in the width direction (Y direction). Specifically, first, as shown in FIG. 6, the control circuit 110 moves the sensor module 32 from the standby position HP to a predetermined position SP. Then, when the control circuit 110 determines that the ADF 27 has transitioned from the open state to the semi-closed state based on the output signal of the open / close sensor 81 while the sensor module 32 is in the standby position HP, it moves the sensor module 32 a fixed distance in the X direction with the first light source 321 and the second light source 322 turned off, as shown in FIG. 8, to scan a portion of the medium P. The fixed distance is appropriately set so as to obtain an image of a length necessary to determine the size of the medium P in the width direction (Y direction), and may be, for example, approximately 10 mm to 20 mm. Then, the image processing circuit 120 obtains an image information signal IS corresponding to the image signal SO output from the sensor module 32 and generates a first image H1. In this way, when the ADF 27 is in the process of closing, the sensor module 32 scans a part of the medium P with the first light source 321 and the second light source 322 turned off, thereby obtaining the first image H1 through the first scan.

[0054] 9, when the ADF 27 is in a semi-closed state, the control circuit 110 turns on the first light source 321 and turns off the second light source 322, and moves the sensor module 32 a certain distance in the X direction to scan a portion of the medium P. The image processing circuit 120 then acquires an image information signal IS corresponding to the image signal SO output from the sensor module 32 and generates a second image H2. In this way, the second image H2 is obtained by the second scan in which the sensor module 32 scans a portion of the medium P with the first light source 321 turned on when the ADF 27 is partially closed.

[0055] Furthermore, when the control circuit 110 determines that the ADF 27 has transitioned from the semi-closed state to the closed state based on the output signal of the open / close sensor 81, it turns on the first light source 321 and turns off the second light source 322, and moves the sensor module 32 a certain distance in the X direction to scan a portion of the medium P, as shown in Fig. 10. Then, the image processing circuit 120 acquires an image information signal IS corresponding to the image signal SO output from the sensor module 32, and generates a third image C1. In this way, the third image C1 is obtained by a third scan in which the sensor module 32 scans a portion of the medium P with the first light source 321 turned on when the ADF 27 is closed.

[0056] Here, by turning off the second light source 322 and turning on only the first light source 321 during the second and third scans, shadows are more likely to appear at the Y-direction edges of the medium P and the surface irregularities of the medium P are more likely to become apparent. In particular, when the medium P is made of thin paper, tracing paper, or the like, shadows are less likely to appear at the Y-direction edges of the medium P, but the surfaces of thin paper and tracing paper have minute irregularities. Therefore, the second image H2 and the third image C1 are obtained, in which the range of the image corresponding to a portion of the medium P is easily identified. Furthermore, as shown in FIG. 10 , during the third scan performed when the ADF 23 is closed, a sheet-like member 64 is in close contact with the back of the medium P as viewed from the sensor module 32. However, because the sheet-like member 64 is made of a highly smooth material, the surface irregularities of the sheet-like member 64 are smaller than the surface irregularities of the medium P. Therefore, the range of the image corresponding to a portion of the medium P is more easily identified in the third image C1.

[0057] On the other hand, in the normal scan mode, when the ADF 27 is closed, the sensor module 32 scans the medium P with the first light source 321 and the second light source 322 turned on, and the information formed on the medium P is read by the fourth scan. By turning on both the first light source 321 and the second light source 322 in the fourth scan, shadows are less likely to appear on the Y-direction end of the medium P, and unevenness on the surface of the medium P is less likely to emerge, and the information formed on the medium P is read. The information is read correctly. In this way, it is preferable that the amount of light emitted by the sensor module 32 in the second or third scan is smaller than the amount of light emitted by the sensor module 32 in the fourth scan. Note that the control circuit 110 may turn on the second light source 322 and turn off the first light source 321 in the second and third scans.

[0058] The control circuit 110 determines the size of the medium P in the width direction (Y direction) based on the first image H1, second image H2, and third image C1 generated by the image processing circuit 120. Details of the process for determining the size of the medium P in the width direction (Y direction) will be described next.

[0059] 4.Determining the width of the media FIG. 11 is a diagram showing examples of the second image H2 and the third image C1 obtained when no external light hits the image reading device 1. As described above, only the first light source 321 is turned on during the second scan, and therefore, as shown in FIG. 11, the image H2_P corresponding to the medium P included in the second image H2 is an image in which the unevenness of the surface of the medium P is highlighted. In contrast, as shown in FIG. 9, during the second scan, there is nothing behind the medium P that reflects the light emitted from the first light source 321, and therefore, as shown in FIG. 11, the image H2_B of the background portion included in the second image H2 is black. Furthermore, as described above, only the first light source 321 is turned on during the third scan, and therefore, as shown in FIG. 11, the image C1_P corresponding to the medium P included in the third image C1 is an image in which the unevenness of the surface of the medium P is highlighted. 10, in the third scan, the sheet-like member 64 is in close contact with the back of the medium P, and therefore the image C1_B of the background portion corresponding to the sheet-like member 64 included in the third image C1 is white, as shown in Fig. 11. Therefore, when external light is not incident on the image reading device 1, the color of the image H2_B of the background portion included in the second image H2 is clearly different from the color of the image C1_B of the background portion included in the third image C1, and therefore the widthwise size of the medium P can be determined from the difference between the second image H2 and the third image C1.

[0060] In contrast, FIG. 12 illustrates examples of the second image H2 and the third image C1 obtained when external light strikes the image reading device 1. In FIG. 12, the third image C1 is the same as in FIG. 11. As shown in FIG. 9, during the second scan, the ADF 27 is semi-closed, so external light passes through the platen 36 in areas where the medium P is not present and is received by the image reading sensor 323 of the sensor module 32. Therefore, as shown in FIG. 12, the image H2_B of the background portion included in the second image H2 is brighter rather than black. Therefore, when external light strikes the image reading device 1, the difference in color between the image H2_B of the background portion included in the second image H2 and the image C1_B of the background portion included in the third image C1 becomes smaller, which may make it impossible to determine the widthwise size of the medium P based on the difference between the second image H2 and the third image C1. Therefore, it is not preferable to determine the widthwise size of the medium P based on the difference between the second image H2 and the third image C1.

[0061] In contrast, FIG. 13 illustrates examples of a first image H1 and a second image H2 obtained when external light strikes the image reading device 1. In FIG. 13, the second image H2 is the same as that in FIG. 12. As shown in FIG. 8, during the first scan, the ADF 27 is semi-closed, so external light passes through the platen 36 in areas where the medium P is not present and is received by the image reading sensor 323 of the sensor module 32. Therefore, as shown in FIG. 13, the image H1_B of the background portion included in the first image H1 is not black but is a lighter color. That is, the image H1_B of the background portion included in the first image H1 is the same color as the image H2_B of the background portion included in the second image H2. Also, as shown in FIG. 8, during the first scan, both the first light source 321 and the second light source 322 are turned off, and only a portion of the external light can pass through the medium P. Therefore, as shown in FIG. 13, the image H1_P corresponding to the medium P included in the first image H1 is dark. Therefore, when external light hits the image reading device 1, the color of the image H1_B of the background portion included in the first image H1 is clearly different from the color of the image H2_B of the background portion included in the second image H2, so the size of the medium P in the width direction is determined based on the difference between the first image H1 and the second image H2. It is possible.

[0062] In contrast, FIG. 14 is a diagram showing examples of a first image H1 and a second image H2 obtained when strong external light hits the image reading device 1. In FIG. 14, the second image H2 is almost the same as in FIG. 14. On the other hand, when the external light is strong, the amount of light that passes through the medium P during the first scan increases, and as shown in FIG. 14, the image H1_B of the background portion included in the first image H1 becomes brighter rather than darker. Therefore, when the external light hitting the image reading device 1 is strong, the difference in color between the image H1_B of the background portion included in the first image H1 and the image H2_B of the background portion included in the second image H2 becomes smaller, which creates the risk that the width size of the medium P cannot be determined based on the difference between the first image H1 and the second image H2.

[0063] 10, even when the external light is strong, the ADF 27 is closed during the third scan, so that the external light does not affect the edges of the medium P in the Y direction, and the unevenness of the surface of the medium P is easily highlighted. Therefore, a third image C1 is obtained, similar to that shown in FIG. 11, in which the range of the image corresponding to a portion of the medium P is easy to see.

[0064] As described above, in this embodiment, if the color difference between the first image H1 and the second image H2 falls within a predetermined range, the control circuit 110 determines the widthwise size of the medium P based on the difference between the first image H1 and the second image H2. If the color difference between the first image H1 and the second image H2 does not fall within the predetermined range, the control circuit 110 performs edge detection on the third image C1 to determine the widthwise size of the medium P. Note that edge detection methods are well known in the image processing field, and therefore will not be described here.

[0065] Thus, the image reading device 1 has a first determination mode in which the size of the medium P is determined based on the difference between the first image H1 obtained by the first scan and the second image H2 obtained by the second scan, and a second determination mode in which the size of the medium P is determined by performing edge detection on the third image C1 obtained by the third scan. The control circuit 110 then determines whether the intensity of external light is within a predetermined range, and if the intensity of external light is within the predetermined range, determines the size of the medium P using the first determination mode. If the intensity of external light is outside the predetermined range, determines the size of the medium P using the second determination mode. For example, the control circuit 110 may determine whether the intensity of external light is within the predetermined range based on at least one of the first image H1 and the second image H2. Note that in the first determination mode, the control circuit 110 may determine the size of the medium P based on the difference between the first image H1 and the second image H2 and the third image C1.

[0066] For example, the control circuit 110 compares the color tone H2(p2) of the pixel p2 of the second image H2 with a predetermined first determination threshold value thL. If H2(p2) < thL, it may be determined that the intensity of the external light is within a predetermined range. If H2(p2) ≥ thL, it may be determined that the intensity of the external light is outside the predetermined range. Also, in the first determination mode, the control circuit 110 compares the difference (H2(p2) - H1(p1)) between the color tone of the pixel p1 of the first image H1 and the color tone of the pixel p2 of the second image H2 corresponding to the pixel p1 with a second determination threshold value C1(p3) × k obtained by multiplying the color tone of the pixel p3 of the third image C1 corresponding to the pixels p1 and p2 by a predetermined coefficient k. If (H2(p2) - H1(p1)) ≥ C1(p3) × k, it may be determined that the pixel p1 is included in the image of the medium P. Further, the control circuit 110 compares the difference (H2(p2) - H1(p1)) between the color tone of the pixel p1 of the first image H1 and the color tone of the pixel p2 of the second image H2 with a predetermined third determination threshold value thB. If (H2(p2) - H1(p1)) ≤ thB, it may be determined that the pixel p1 is included in the background image. Then, the control circuit 110 can determine the size of the medium P in the width direction from the Y coordinate of the pixel p1 at the boundary between the medium P and the background image. Thus, in the first determination mode, the control circuit 110 may determine the size of the medium P in the width direction based on the difference between the first image H1 and the second image H2 and the third image C1.

[0067] Figs. 15 to 18 show an example of the color tone H1(p1) of each pixel p1 of the first image H1, the color tone H2(p2) of each pixel p2 of the second image H2, the color tone C1(p3) of each pixel p3 of the third image C1, and the determination result. Fig. 15 shows an example where the medium P is white and there is no external light. Fig. 16 shows an example where the medium P is white and there is external light. Fig. 17 shows an example where the medium P is white and the external light is strong. Fig. 18 shows an example where the medium P is black and there is no external light. In Figs. 15 to 18, for simplicity, it is assumed that an image including 10 pixels arranged in a row in the Y direction is obtained by scanning in the X direction. Also, in Figs. 15, 16, and 18, "P" in the pixel determination column indicates that the pixel corresponds to the medium P, and "B" in the pixel determination column indicates that the pixel corresponds to the background. In Figs. 15 to 18, the first determination threshold thL = 250, the coefficient k = 0.8, and the third determination threshold thB = 20.

[0068] In the examples of Figs. 15 and 16, since H2(p2) < thL, it is determined that the intensity of the external light is within the predetermined range, and the first determination mode is selected. Six pixels p1 with Y coordinates from 0 to 5 are determined to be pixels corresponding to the medium P, and four pixels p1 with Y coordinates from 6 to 10 are determined to be pixels corresponding to the background. In the example of Fig. 17, since H2(p2) = thL, it is determined that the intensity of the external light is outside the predetermined range, and the second determination mode is selected. In the example of Fig. 18, although the medium P is black, since H2(p2) = thL, it is determined that the intensity of the external light is outside the predetermined range. Similar to the examples of Figs. 15 and 16, six pixels p1 with Y coordinates from 0 to 5 are determined to be pixels corresponding to the medium P, and four pixels p1 with Y coordinates from 6 to 10 are determined to be pixels corresponding to the background.

[0069] Note that the first determination mode is an example of the "first mode", the second determination mode is an example of the "second mode", and the normal scan mode is an example of the "third mode".

[0070] 5. Relationship between the return process from the sleep state and the medium size determination process Up to this point, the process of determining the size of the medium P has been described on the assumption that the control circuit 110 and image processing circuit 120 mounted on the scanner board 100 are immediately operational when the user opens the ADF 27. However, it is also conceivable that the scanner board 100 is in a sleep state when the user opens the ADF 27, and the process of determining the size of the medium P is performed after the scanner board 100 returns from the sleep state.

[0071] 19 is a time chart showing an example of the time series of the process of returning the scanner board 100 from the sleep state and the process of determining the size of the medium P. As shown in Fig. 19, when the ADF 27 transitions from the closed state to the open state, the process of returning the scanner board 100 from the sleep state begins. After about 1.5 seconds have passed since the return process began, the photosensor 80 becomes capable of detecting the medium P.

[0072] The recovery process continues, and after 3.0 seconds, the recovery process ends, enabling the sensor module 32 to operate. At this time, the sensor module 32 is in a standby position HP facing the white reference plate 90. First, the control circuit 110 activates the sensor module 32, and the image processing circuit 120 acquires data for shading correction. Next, the control circuit 110 moves the sensor module 32 from the standby position HP to a predetermined position SP, enabling the sensor module 32 to read data to determine the size of the medium P. It takes approximately four seconds from the start of the recovery process until the sensor module 32 is ready to read data.

[0073] Thereafter, when the ADF 27 transitions from the open state to the half-closed state, the control circuit 110 acquires the output signal O1 of the photosensor 80 and causes the sensor module 32 to read the medium P, and the image processing circuit 120 generates a first image H1 and a second image H2. Thereafter, when the ADF 27 transitions from the half-closed state to the closed state, the control circuit 110 acquires the output signal O2 of the photosensor 80 and causes the sensor module 32 to read the medium P, and the image processing circuit 120 generates a third image C1. Thereafter, as described above, the control circuit 110 determines the height-wise size of the medium P based on the output signals O1 and O2 of the photosensor 80, and determines the width-wise size of the medium P based on the first image H1, the second image H2, and the third image C1.

[0074] In the example of Figure 19, the ADF 27 is in a half-closed state after the sensor module 32 becomes capable of reading, but as shown in Figure 20, depending on the timing at which the user closes the ADF 27, it is possible that the ADF 27 will be in a half-closed state before the sensor module 32 becomes capable of reading.

[0075] 20, the ADF 27 transitions to a semi-closed state during the process of returning the scanner board 100 from a sleep state, preventing the sensor module 32 from reading the medium P, and preventing the image processing circuit 120 from generating the first image H1 and the second image H2. Also, in the example of FIG. 20, the ADF 27 transitions to a closed state before the sensor module 32 becomes capable of reading, but the sensor module 32 then moves to a predetermined position SP and reads the medium P, allowing the image processing circuit 120 to generate the third image C1.

[0076] Therefore, in this case, the control circuit 110 cannot determine the size of the medium P in the first determination mode, and determines the size of the medium P in the second determination mode. That is, if the ADF 27 is closed before the scanner board 100 returns from the sleep state due to the opening of the ADF 27 and the sensor module 32 becomes operational, the control circuit 110 determines the widthwise size of the medium P in the second determination mode. On the other hand, if the ADF 27 is closed after the scanner board 100 returns from the sleep state due to the opening of the ADF 27 and the sensor module 32 becomes operational, a first image H1 and a second image H2 are generated as shown in FIG. 19 , and the control circuit 110 determines the widthwise size of the medium P in the first determination mode.

[0077] Since the time from when the ADF 27 transitions from the closed state to the open state until the photosensor 80 is able to detect the medium P is short, it is unlikely that the ADF 27 will transition to the half-closed state during this time. Therefore, the control circuit 110 can obtain the output signals O1 and O2 of the photosensor 80 and determine the size of the medium P in the height direction.

[0078] 6. Image reading method 21 is a flowchart showing an example of the steps of the image reading method of this embodiment. As shown in FIG. 21, first, in step S10, the control circuit 110 waits until the ADF 27 is opened. Once the ADF 27 is opened in step S10, the control circuit 110 determines the size of the medium P in the first determination mode or the second determination mode in step S20. Finally, in step S30, the sensor module 32 reads the information formed on the medium P under the control of the control circuit 110. That is, after the size of the medium P is determined in the first determination mode or the second determination mode in step S20, the control circuit 110 executes a normal scan mode in step S30, in which the sensor module 32 scans the medium P with the first light source 321 and the second light source 322 turned on while the ADF 27 is closed, thereby reading the information formed on the medium P through a fourth scan.

[0079] Fig. 22 is a flowchart showing an example of the detailed procedure of step S20 in Fig. 21. As shown in Fig. 22, first, the control circuit 110 sets the size of the medium P to indefinite. Next, in step S202, the control circuit 110 waits until the ADF 27 is in a half-closed state. Next, in step S203, the control circuit 110 acquires the output signal O1 of the photosensor 80. Next, in step S204, the control circuit 110 determines whether the sensor module 32 is ready for reading. That is, the control circuit 110 determines whether the sensor module 32 has been moved to a predetermined position SP.

[0080] If the sensor module 32 is able to read in step S204, the control circuit 110 turns off the first light source 321 and the second light source 322 in step S205 to cause the sensor module 32 to read a portion of the medium P, and the image processing circuit 120 generates a first image H1. Next, in step S206, the control circuit 110 turns on only the first light source 321 to cause the sensor module 32 to read a portion of the medium P, and the image processing circuit 120 generates a second image H2. Next, in step S207, the control circuit 110 determines whether the intensity of external light is within a predetermined range. For example, the control circuit 110 may determine whether the intensity of external light is within a predetermined range based on at least one of the first image H1 and the second image H2.

[0081] If the intensity of external light is within a predetermined range in step S207, then in step S208, the control circuit 110 waits until the ADF 27 is closed. Once the ADF 27 is closed in step S208, then in step S209, the control circuit 110 acquires the output signal O2 of the photosensor 80. Next, in step S210, the control circuit 110 turns on only the first light source 321 to cause the sensor module 32 to read a portion of the medium P, and the image processing circuit 120 generates a third image C1. Next, in step S211, the control circuit 110 determines the width direction size of the medium P in a first determination mode. That is, the control circuit 110 executes a first determination mode in which the widthwise size of the medium P is determined based on the difference between a first image H1 obtained by a first scan in which the sensor module 32 scans a portion of the medium P with the first light source 321 and the second light source 322 turned off when the ADF 27 is closing in step S205, and a second image H2 obtained by a second scan in which the sensor module 32 scans a portion of the medium P with the first light source 321 turned on when the ADF 27 is closing in step S206. As described above, in the first determination mode, the control circuit 110 may determine the size of the medium P based on the difference between the first image H1 and the second image H2 and the third image C1.

[0082] On the other hand, if the intensity of external light is outside the predetermined range in step S207, the control circuit 110 waits until the ADF 27 is closed in step S212. Once the ADF 27 is closed in step S212, the control circuit 110 acquires the output signal O2 of the photosensor 80 in step S213. Next, in step S214, the control circuit 110 turns on only the first light source 321 to cause the sensor module 32 to read a portion of the medium P, and the image processing circuit 120 generates a third image C1. Next, in step S215, the control circuit 110 determines the width size of the medium P in the second determination mode. That is, the control circuit 110 executes the second determination mode in which, when the ADF 27 is closed in step S214, the control circuit 110 performs edge detection on the third image C1 obtained by the third scan in which the sensor module 32 scans a portion of the medium P with the first light source 321 turned on, thereby determining the width size of the medium P.

[0083] Furthermore, if the sensor module 32 is not readable in step S204, the control circuit 110 also performs the processes of steps S212 to S215.

[0084] Finally, in step S216, the control circuit 110 determines the size of the medium P in the height direction based on the output signals O1 and O2 of the photosensor 80.

[0085] As shown in FIG. 22, when the intensity of external light is within a predetermined range, the control circuit 110 The control circuit 110 determines the size of the medium P in the determination mode. On the other hand, if the intensity of the external light is outside the predetermined range, the control circuit 110 determines the size of the medium P in the second determination mode.

[0086] Also, as shown in FIG. 22, when the ADF 27 is closed after the scanner substrate 100 returns from the sleep state and the operation of the sensor module 32 becomes possible, the control circuit 110 determines the size of the medium P in the first determination mode. However, when the intensity of the external light is outside the predetermined range, the control circuit 110 may determine the size of the medium P in the second determination mode. On the other hand, when the ADF 27 is closed before the scanner substrate 100 returns from the sleep state and the operation of the sensor module 32 becomes possible, the control circuit 110 determines the size of the medium P in the second determination mode.

[0087] 7. Operational Effects As described above, in the image reading apparatus 1 of the present embodiment, for example, the control circuit 110 compares the color tone H2(p2) of the pixel p2 of the second image H2 with the first determination threshold thL, and determines that the external light is weak if H2(p2) < thL, and determines that the external light is strong if H2(p2) ≥ thL. Then, when the external light incident when the ADF 27 is almost closed is weak, based on the difference between the first image H1 obtained with the first light source 321 and the second light source 322 turned off and the second image H2 obtained with the first light source 321 turned on in the first determination mode, the size of the medium P can be easily and accurately determined. Further, when the external light incident when the ADF 27 is almost closed is strong, the control circuit 110 can determine the size of the medium P based on the third image C1 obtained in a state not affected by the external light in the second determination mode. Therefore, according to the image reading apparatus 1 of the present embodiment, the size of the medium P can be correctly determined even in an environment where external light is incident.

[0088] Furthermore, in the image reading device 1 of this embodiment, if the ADF 27 is closed after the scanner board 100 has returned from the sleep state and the sensor module 32 is ready to operate, the control circuit 110 can easily and accurately determine the size of the medium P in the first determination mode based on the difference between the first image H1 obtained with the first light source 321 and the second light source 322 turned off and the second image H2 obtained with the first light source 321 turned on. Alternatively, if the external light is strong, the control circuit 110 can determine the size of the medium P in the second determination mode based on the third image C1 obtained without the influence of external light. Furthermore, if the ADF 27 is closed before the scanner board 100 has returned from the sleep state and the sensor module 32 is ready to operate, the control circuit 110 can determine the size of the medium P in the second determination mode based on the third image C1, even though the first image H1 and the second image H2 are not obtained. Therefore, according to the image reading device 1 of this embodiment, the size of the medium P can be correctly determined regardless of the timing when the scanner board 100 that controls the sensor module 32 returns from the sleep state.

[0089] Furthermore, in the image reading device 1 of this embodiment, for example, in the first determination mode, the control circuit 110 compares the difference (H2(p2)-H1(p1)) between the color tone of pixel p1 in the first image H1 and the color tone of pixel p2 in the second image H2 with a second determination threshold C1(p3)×k obtained by multiplying the color tone of pixel p3 in the third image C1 by a coefficient k, and determines that pixel p1 is included in the image of the medium P if (H2(p2)-H1(p1))≧C1(p3)×k. In this way, the control circuit 110 can more accurately determine the size of the medium P by using the third image C1 in addition to the difference between the first image H1 and the second image H2.

[0090] Furthermore, in the image reading device 1 of this embodiment, the second scan and the third scan are performed by the sensor module 32 with only the first light source 321 turned on and the amount of light is reduced compared to the normal scan mode. This makes it easier for shadows to form on the edges of the medium P, and also makes it easier for unevenness on the surface of the medium P to stand out, resulting in the second image H2 and the third image H3 that make it easier to see the range of the image corresponding to the medium P. Thus, the image reading device 1 of this embodiment can determine the size of the medium P more accurately.

[0091] The present invention includes configurations that are substantially the same as the configurations described in this embodiment, for example, configurations with the same functions, methods, and results, or configurations with the same purpose and effects. The present invention also includes configurations in which non-essential parts of the configurations described in this embodiment are replaced. The present invention also includes configurations that achieve the same effects or purposes as the configurations described in this embodiment. The present invention also includes configurations in which publicly known technology is added to the configurations described in this embodiment.

[0092] The present invention is not limited to the present embodiment, and various modifications are possible within the scope of the present invention.

[0093] The above-described embodiment and modifications are merely examples, and the present invention is not limited to these. For example, the embodiments and modifications can be combined as appropriate.

[0094] The following can be derived from the above-described embodiment and modifications.

[0095] One aspect of the image reading device is a first mode for determining the size of the medium based on the difference between a first image obtained by a first scan in which the sensor module scans a portion of the medium with the light source turned off when the top panel is in the process of closing, and a second image obtained by a second scan in which the sensor module scans a portion of the medium with the light source turned on when the top panel is in the process of closing; a second mode in which the size of the medium is determined by performing edge detection on a third image obtained by a third scan in which the sensor module scans a portion of the medium while the light source is turned on when the top panel is closed; and and determining whether the intensity of external light is within a predetermined range; If the intensity of the external light is within the predetermined range, determining the size of the medium in the first mode; If the intensity of the external light is outside the predetermined range, the size of the medium is determined in the second mode.

[0096] In this image reading device, when the external light incident when the top panel is closing is weak, the first mode can be used to easily and accurately determine the size of the medium based on the difference between the first image obtained with the light source turned off and the second image obtained with the light source turned on. Furthermore, in this image reading device, when the external light incident when the top panel is closing is strong, the second mode can be used to determine the size of the medium based on the third image obtained in a state unaffected by external light. Therefore, this image reading device can accurately determine the size of the medium even in an environment where external light is incident.

[0097] In one aspect of the image reading device, In the first mode, The size of the medium may be determined based on the difference between the first image and the second image and the third image.

[0098] According to this image reading device, in the first mode, the size of the medium can be determined more accurately by further using the third image.

[0099] In one aspect of the image reading device, a third mode in which, after the size of the medium is determined in the first mode or the second mode, the sensor module scans the medium with the light source turned on when the top panel is closed, thereby reading information formed on the medium; The amount of light emitted by the sensor module during the third scanning may be smaller than the amount of light emitted by the sensor module during the fourth scanning.

[0100] With this image reading device, the sensor module performs the third scan with a reduced light intensity, which makes it easier to cast shadows on the edges of the medium and highlights the unevenness of the medium's surface, resulting in a third image in which the image range corresponding to the medium is easy to understand. Therefore, with this image reading device, the medium size can be determined more accurately in the second mode.

[0101] One aspect of the image reading method includes: determining whether the intensity of external light is within a predetermined range; If the intensity of the external light is within the predetermined range, a first mode is executed to determine the size of the medium based on the difference between a first image obtained by a first scan in which the sensor module scans a portion of the medium with the light source turned off when the top panel is closing, and a second image obtained by a second scan in which the sensor module scans a portion of the medium with the light source turned on when the top panel is closing, If the intensity of the external light is outside the specified range, a second mode is executed in which the sensor module, with the light source turned on when the top panel is closed, performs edge detection on a third image obtained by a third scan in which the sensor module scans a portion of the medium, thereby determining the size of the medium.

[0102] With this image reading method, when the external light incident when the top panel is closing is weak, the first mode can be used to easily and accurately determine the size of the medium based on the difference between the first image obtained with the light source off and the second image obtained with the light source on. Furthermore, with this image reading method, when the external light incident when the top panel is closing is strong, the second mode can be used to determine the size of the medium based on the third image obtained in a state unaffected by external light. Therefore, with this image reading method, the size of the medium can be accurately determined even in an environment where external light is incident.

[0103] In one aspect of the image reading method, In the first mode, The size of the medium may be determined based on the difference between the first image and the second image and the third image.

[0104] According to this image reading method, in the first mode, the size of the medium can be determined more accurately by further using the third image.

[0105] In one aspect of the image reading method, After the size of the medium is determined in the first mode or the second mode, a third mode is executed in which the sensor module scans the medium with the light source turned on while the top panel is closed, and reads information formed on the medium by a fourth scan; The amount of light emitted by the sensor module during the third scanning may be smaller than the amount of light emitted by the sensor module during the fourth scanning.

[0106] According to this image reading method, the third scanning by the sensor module is performed under reduced light conditions. Since the scanning is performed, shadows are more likely to appear on the edges of the medium and the irregularities on the surface of the medium are more likely to appear, resulting in a third image that makes it easier to see the range of the image corresponding to the medium. Therefore, with this image reading method, the size of the medium can be determined more accurately in the second mode. [Explanation of symbols]

[0107] 1...image reading device, 10...multifunction device, 12...device main body, 12a...upper portion, 13...recording device, 16...operation section, 18...opening, 20...drawer section, 22...front tray, 24...rear tray, 26...paper storage section, 27...ADF, 28...document transport section, 30...image reading section, 32...sensor module, 34...image reading surface, 36...document table, 38...document transport path, 40...document placement surface, 42...document ejection surface, 44...cover, 46...feed roller, 48...separation roller, 50...first transport auxiliary roller, 52...first transport roller pair, 54...second transport auxiliary roller, 56...second transport roller pair, 58...third transport roller pair, 60...ejection roller pair , 62... document pressing portion, 64... sheet-like member, 66... ​​elastic member, 68... reinforcing member, 70a... fixing member, 80, 80a, 80b... photosensor, 81... opening / closing sensor, 90... white reference plate, 100... scanner board, 110... control circuit, 120... image processing circuit, 121... calculation unit, 122... memory unit, 130... analog front end, 321... first light source, 321R... red LED, 321G... green LED, 321B... blue LED, 322... second light source, 322R... red LED, 322G... green LED, 322B... blue LED, 323... image reading sensor, 324... first light guide, 325... second light guide, 326... lens

Claims

1. a first mode for determining the size of the medium based on the difference between a first image obtained by a first scan in which the sensor module scans a portion of the medium with the light source turned off when the top panel is in the process of closing, and a second image obtained by a second scan in which the sensor module scans a portion of the medium with the light source turned on when the top panel is in the process of closing; a second mode in which the size of the medium is determined by performing edge detection on a third image obtained by a third scan in which the sensor module scans a portion of the medium while the light source is turned on when the top panel is closed; and and determining whether the intensity of external light is within a predetermined range; If the intensity of the external light is within the predetermined range, the size of the medium is determined in the first mode; If the intensity of the external light is outside the predetermined range, the size of the medium is determined in the second mode. An image reading device characterized by:

2. In the first mode, determining the size of the medium based on the difference between the first image and the second image and the third image; 2. The image reading device according to claim 1, wherein:

3. a third mode in which, after the size of the medium is determined in the first mode or the second mode, the sensor module scans the medium with the light source turned on when the top panel is closed, and reads information formed on the medium by a fourth scan; the amount of light emitted by the sensor module in the third scanning is smaller than the amount of light emitted by the sensor module in the fourth scanning; 2. The image reading device according to claim 1, wherein:

4. determining whether the intensity of external light is within a predetermined range; If the intensity of the external light is within the predetermined range, a first mode is executed to determine the size of the medium based on the difference between a first image obtained by a first scan in which the sensor module scans a portion of the medium with the light source turned off when the top panel is closing, and a second image obtained by a second scan in which the sensor module scans a portion of the medium with the light source turned on when the top panel is closing, If the intensity of the external light is outside the predetermined range, a second mode is executed in which the sensor module performs a third scan, in which the sensor module scans a portion of the medium with the light source turned on while the top panel is closed, and performs edge detection on a third image obtained by the third scan to determine the size of the medium. An image reading method comprising:

5. In the first mode, determining the size of the medium based on the difference between the first image and the second image and the third image; 5. The image reading method according to claim 4, wherein:

6. After the size of the medium is determined in the first mode or the second mode, a third mode is executed in which the sensor module scans the medium with the light source turned on while the top panel is closed, and information formed on the medium is read by a fourth scan. 、 the amount of light emitted by the sensor module in the third scanning is smaller than the amount of light emitted by the sensor module in the fourth scanning; 5. The image reading method according to claim 4, wherein:

Images