Image reading device, document detection method, and document reading method

Abstract

The system detects when the document cover is open and a document is placed on the document tray's surface. [Solution] The control unit of the image reading device performs a first reading process in which the reading unit performs reading with the light-emitting unit turned off while the document cover is open and before the document is placed on the placement surface. The control unit performs a second reading process in which the reading unit performs reading while the document cover is open and the light-emitting unit is turned off. The control unit detects that a document has been placed on the placement surface based on the difference between the first reading result obtained by the first reading process and the second reading result obtained by the second reading process.

Description

Technical Field

[0001] The present invention relates to an image reading apparatus having a reading unit for reading a document, a document detection method, and a document reading method.

Background Art

[0002] For example, Patent Document 1 discloses a method of detecting the size of a document by a line sensor (an example of a reading unit) that reads the document in an image reading apparatus. When an opening / closing detection unit (an example of an opening / closing sensor) detects that a document pressing unit (an example of a document cover) has been tilted from a predetermined position, reading by the line sensor is performed while irradiating the document with light from a lamp (an example of a light emitting unit).

[0003] In the technique of Patent Document 1, disturbance light detection image data is generated by causing the line sensor to perform reading in an open state where the document pressing unit is lifted above a predetermined position and in a state where the lamp is turned off. Document size detection image data is generated by causing the line sensor to perform reading in a closed state where the document pressing unit is tilted from a predetermined position and in a state where the lamp is turned on. Based on the disturbance light detection image data and the document size detection image data, the document size is detected. Therefore, with the technique of Patent Document 1, the document size can be detected without being affected by disturbance light.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, there are times when it is necessary to detect when a document is placed on the document tray surface while the document cover is open. The technology described in Patent Document 1 can detect the size of the document, and therefore it is presumed that it can detect the presence or absence of a document. This technology requires reading with the light-emitting part off when the document cover is open, and reading with the light-emitting part on when the document cover is closed. For this reason, it is necessary to close the document cover in order to detect the presence or absence of a document, and power consumption increases when the light-emitting part is turned on. Therefore, there is a demand for document detection that can detect when a document is placed on the document tray surface even when the document cover is open, with low power consumption. [Means for solving the problem]

[0006] An image reading device that solves the above problems comprises a document tray having a surface on which a document is placed, a reading unit that reads a document placed on the front surface of the document tray from the opposite side of the front surface, a light-emitting unit that can be switched on and off and illuminates the document from the opposite side of the front surface of the document tray when lit, a document cover that opens and closes the front surface of the document tray, and a control unit. The control unit detects that a document has been placed on the front surface based on the difference between a first reading result obtained by a first reading process in which the reading unit performs reading with the light-emitting unit turned off when the document cover is open and a document is not placed on the front surface, and a second reading result obtained by a second reading process in which the reading unit performs reading with the document cover open and the light-emitting unit turned off, and then executes a document reading process in which the reading unit reads the document based on the difference between the first reading result obtained by a first reading process in which the reading unit performs reading with the light-emitting unit turned off when the document cover is open and a document is not placed on the front surface, and detects that a document has been placed on the front surface.

[0007] A document detection method for solving the above problems is an image reading device that detects a document placed on the document table, comprising: a document table having a surface on which a document is placed; a reading unit that reads a document placed on the surface of the document table from the opposite side of the surface; a light-emitting unit that can be switched on and off, and when lit, illuminates the document through the document table from the opposite side of the surface of the document table; and a document cover that opens and closes the surface of the document table. The method for detecting a document placed on the document table is performed by an image reading device, wherein, when the document cover is in the open state and before a document is placed on the surface of the document table, a first reading process is performed in which the reading unit is made to perform reading with the light-emitting unit turned off, and based on the result of this process, it is determined that a document placed on the surface of the document table can be detected. In this case, a second reading process is performed in which the reading unit is made to perform reading with the document cover in the open state and the light-emitting unit turned off, and the document placed on the surface of the document table is detected based on the difference between the result of the second reading process and the result of the first reading process.

[0008] A document reading method that solves the above problem is a document reading device comprising: a document table having a surface on which a document is placed; a reading unit that reads a document placed on the front surface of the document table from the opposite side of the front surface; a light-emitting unit that can be switched on and off, and when lit, illuminates the document through the document table from the opposite side of the front surface of the document table; and a document cover that opens and closes the front surface of the document table, wherein the document reading method reads a document placed on the document table using an image reading device, wherein the document cover is in the open state and before the document is placed on the front surface, the light-emitting unit Based on the result of the first reading process, in which the reading unit performs reading with the lights off, if it is determined that the document placed on the aforementioned surface can be detected, a second reading process is performed in which the reading unit performs reading with the document cover open and the light-emitting unit turned off. Based on the difference between the result of the second reading process and the result of the first reading process, it is detected that a document has been placed on the aforementioned surface, and based on the result of detecting that a document has been placed on the aforementioned surface, a document reading process is performed in which the reading unit reads the document. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic cross-sectional view showing an image reading device in an embodiment. [Figure 2] Figure 2 is a schematic plan view showing an image reading device. [Figure 3] Figure 3 is a partially broken schematic front view of an image reading device on which a document is placed. [Figure 4] Figure 4 is a schematic plan view showing the configuration of the reading module. [Figure 5] Figure 5 is a block diagram showing the electrical configuration of the image reading device. [Figure 6] Figure 6 is a schematic diagram of the image reading device when the document cover is open and the document has not yet been placed on it, and a graph showing the reading data at that time. [Figure 7] Figure 7 is a schematic diagram of the image reading device and a graph showing the reading data when a document is placed with the document cover open. [Figure 8] Figure 8 is a graph showing the difference between the first reading result and the second reading result. [Figure 9] Figure 9 is a graph showing the difference data. [Figure 10] Figure 10 is a flowchart showing the document reading control routine, including the document placement detection process. [Modes for carrying out the invention]

[0010] An embodiment of the image reading device will be described below with reference to the drawings. <Image reading device> Figure 1 shows the image reading device 11 in its operating position. The X, Y, and Z axes shown in Figure 1 are orthogonal to each other. The Z axis is parallel to the direction of gravity. The Y axis is parallel to the width direction of the image reading device 11 when viewed from the front as shown in Figure 1. The X axis is parallel to the depth direction of the image reading device 11. The directions parallel to the X, Y, and Z axes are referred to as the X direction, Y direction, and Z direction, respectively. The X direction includes both the +X direction and the -X direction. The Y direction includes both the +Y direction and the -Y direction. The Z direction includes both the +Z direction and the -Z direction. Note that the Y direction is also called the width direction Y, the X direction is also called the depth direction X, and the Z direction is also called the vertical direction Z.

[0011] As shown in Figure 1, the image reading device 11 comprises a document tray 12 and a document cover 15. The document tray 12 has a mounting surface 12A on which the document M1 is placed. The document M1 is set on the document tray 12 by being placed on the mounting surface 12A.

[0012] The document tray 12 comprises a housing 13 and a transparent plate 14. The transparent plate 14 is attached to the top of the housing 13. The transparent plate 14 constitutes the top plate of the housing 13. The upper surface of the transparent plate 14 forms the mounting surface 12A. That is, the upper surface of the portion of the upper surface of the document tray 12 in which the transparent plate 14 is exposed is the mounting surface 12A. The mounting surface 12A is sized to accommodate the largest document M1 that the image reading device 11 can read.

[0013] The document cover 15 is configured to rotate relative to the document tray 12. The document cover 15 opens and closes the mounting surface 12A of the document tray 12. The document cover 15 is attached to the document tray 12 via a rotation mechanism (not shown). In the front view shown in Figure 1, the rotation axis of the document cover 15 is located on the +X side of the depth direction X and extends in the width direction Y. The document cover 15 can be opened and closed within a predetermined angle range around the rotation axis on the rear side.

[0014] When the original document cover 15 is opened, the placement surface 12A, which is the upper surface of the transparent plate 14, is exposed. As a result, the user can place (set) the original document M1 on the placement surface 12A. By closing the original document cover 15 with respect to the original document table 12, the original document M1 placed on the placement surface 12A is pressed from above. In the state shown in FIG. 1, the original document M1 placed on the placement surface 12A is pressed against the placement surface 12A by the closed original document cover 15. In this state, the original document M1 is read by the image reading device 11.

[0015] The image reading device 11 includes a reading unit 17 and a light emitting unit 18. The image reading device 11 may include a carriage 19 that supports the reading unit 17 and the light emitting unit 18. The reading unit 17 is configured to read the original document M1 placed on the placement surface 12A. The reading unit 17 reads the original document M1 placed on the placement surface 12A of the original document table 12 on the opposite side of the placement surface 12A. The reading unit 17 is located within the housing 13 of the original document table 12. The reading unit 17 is located on the opposite side of the placement surface 12A with the transparent plate 14 interposed therebetween. The reading unit 17 is configured to scan within the housing 13.

[0016] As shown in FIG. 1, the carriage 19 that supports the reading unit 17 is configured to be movable in the width direction Y. The reading unit 17 is configured to move in the width direction Y along the placement surface 12A in a state of facing the placement surface 12A on the transparent plate 14 together with the carriage 19. The reading unit 17 reads the original document M1 through the transparent plate 14 by scanning the original document M1 placed on the placement surface 12A. The reading unit 17 is movable over a range wider than the placement surface 12A in the width direction Y.

[0017] The reading unit 17 has a shape that is long in one direction and is constituted by, for example, a line sensor. In the example shown in FIG. 1, the reading unit 17 is arranged such that its longitudinal direction is parallel to the depth direction X. The longitudinal direction of the reading unit 17 formed by the line sensor is referred to as the main scanning direction, and the moving direction of the reading unit 17 is referred to as the sub-scanning direction. Since the main scanning direction is parallel to the depth direction X, it is also referred to as the "main scanning direction X". Since the sub-scanning direction is parallel to the width direction Y, it is also referred to as the "sub-scanning direction Y". The reading unit 17 can move in the +Y direction and -Y direction of the sub-scanning direction Y by the movement of the carriage 19. Note that the main scanning direction X and the sub-scanning direction Y intersect (for example, are orthogonal) to each other.

[0018] The carriage 19 moves the reading unit 17 along the platen 12. The carriage 19 moves the reading unit 17 in the sub-scanning direction Y. By moving the reading unit 17 formed by the line sensor extending in the main scanning direction X in the sub-scanning direction Y, the carriage 19 can read the area including the entire surface of the document M1 placed on the placement surface 12A.

[0019] The light emitting unit 18 can switch between lighting and extinguishing. The light emitting unit 18 is located inside the housing 13 of the platen 12. The light emitting unit 18 illuminates the document M1 from the side opposite to the placement surface 12A of the platen 12 in the lighting state. The light emitting unit 18 illuminates the portion of the document M1 that the reading unit 17 is to read from the side opposite to the placement surface 12A.

[0020] The light emitting unit 18 is configured to scan inside the housing 13. The light emitting unit 18 illuminates the document M1 placed on the placement surface 12A of the platen 12 through the transparent plate 14. By being supported above the carriage 19, the light emitting unit 18 moves along the placement surface 12A of the platen 12 together with the reading unit 17. The light emitting unit 18 moves in the sub-scanning direction Y as the carriage 19 moves. The light emitting unit 18 is supported by the carriage 19 at a position that satisfies the positional relationship that it can illuminate the area including the portion of the read surface of the document M1 placed on the placement surface 12A that the reading unit 17 is to read. When the light emitting unit 18 lights up, it illuminates the reading target area extending along the main scanning direction X of the reading unit 17 formed by the line sensor.

[0021] The reading unit 17 and the light-emitting unit 18 constitute the reading module 20 (see also Figure 4). The reading module 20 is supported on the upper part of the carriage 19. In this embodiment, the reading unit 17 of the reading module 20 is, for example, a CIS (Contact Image Sensor) type (contact optical type) contact image sensor module (CISM). The detailed configuration of the reading module 20 will be described later.

[0022] The image reading device 11 may include a reading window 21. The reading window 21 may be located outside the mounting surface 12A in a plan view (see also Figure 2). In the example shown in Figure 1, the reading window 21 is located outside the mounting surface 12A in the sub-scanning direction Y. The reading window 21 may be provided in a position where the reading unit 17 can face it. The reading window 21 is located on the upper part of the document tray 12, adjacent to the transparent plate 14 in the sub-scanning direction Y. The reading window 21 and the transparent plate 14 are both mounted horizontally and at approximately the same height on the upper part of the housing 13.

[0023] The reading unit 17 is configured to be movable to a position facing the reading window 21, as shown by the dashed line in Figure 1, by the movement of the carriage 19. The carriage 19 is movable in the sub-scanning direction Y over a range of movement that includes the position where the reading unit 17 faces the reading window 21 and the region where the reading unit 17 faces the mounting surface 12A. As a result, the reading unit 17 is able to move (scan) in the sub-scanning direction Y over a scanning range that includes the position facing the reading window 21 and the region facing the transparent plate 14, by the movement of the carriage 19.

[0024] The reading window section 21 has a small transparent plate 22 that is significantly smaller than the size of the transparent plate 14. The transparent plates 14 and 22 are made of glass, for example. The transparent plate 14 is made of a large piece of glass that is larger than the size of the transparent plate 22 which is made up of small pieces of glass that make up the reading window section 21, and the transparent plate 22 is made of small pieces of glass that are smaller than the large piece of glass. The position and length of the transparent plate 14 and the reading window section 21 in the main scanning direction X are approximately the same.

[0025] The image reading device 11 may be equipped with an open / close sensor 23. The open / close sensor 23 detects the opening and closing of the document cover 15. The open / close sensor 23 is configured to detect the open and closed states of the document cover 15. The open / close sensor 23 may detect that the document cover 15 is open relative to the document glass 12, or it may detect that the document cover 15 is closed relative to the document glass 12. The open / close sensor 23 may be attached to the housing 13, for example, but it may also be attached to the document cover 15. The open / close sensor 23 may be a contact type sensor or a non-contact type sensor such as an optical sensor. The open / close sensor 23 may be provided, for example, at a position on the rear side closer to the rotation axis of the document cover 15 in the depth direction X of the image reading device 11, or at a position on the rotation end side of the document cover 15.

[0026] The opening / closing sensor 23 may detect the open state when the opening angle, which is the angle that the document cover 15 makes with respect to the mounting surface 12A, is greater than or equal to a predetermined angle, and the closed state when it is less than the predetermined angle. The predetermined angle is a predetermined value within the range from 0 degrees, which is the angle when the document cover 15 is completely closed with respect to the document tray 12, to the maximum opening angle. The predetermined angle can be set to an appropriate value, but as an example, it may be a predetermined value within the range of 1 degree to 45 degrees. In this embodiment, the predetermined angle may be a predetermined value within the range of 5 degrees to 30 degrees.

[0027] The image reading device 11 includes a display unit 41. The display unit 41 is configured to display a screen. The display unit 41 is, for example, a liquid crystal display. The display unit 41 is, for example, mounted on the document glass 12. The display unit 41 notifies the user of information about the image reading device 11 by displaying information on its screen.

[0028] The image reading device 11 includes an operation unit 42. The operation unit 42 is operated by the user. The user operates the image reading device 11 through the operation unit 42. The operation unit 42 is, for example, a touch panel. That is, the operation unit 42 may be composed of a touch operation function unit of a display unit 41 which is composed of a touch panel. The operation unit 42 may be composed of at least one operation button or the like that is displayed on the screen of the display unit 41 for operating the image reading device 11. The user gives instructions to the image reading device 11 by touching the screen displayed on the display unit 41. The operation unit 42 is not limited to a touch panel and may include buttons, levers, switches, etc.

[0029] The image reading device 11 includes a control unit 50. The control unit 50 is configured to control the image reading device 11. The control unit 50 controls the reading unit 17 and the light-emitting unit 18. The control unit 50 controls the movement of the carriage 19 along the mounting surface 12A. The control unit 50 controls the display unit 41. The control unit 50 causes the display unit 41 to display various information. The control unit 50 controls the image reading device 11 based on instructions given by the user to the image reading device 11 through the operation of the operation unit 42.

[0030] The image reading device 11 includes the flatbed (FB) image reading function described above and the automatic document feeder (ADF) image reading function described below. The configuration of the ADF image reading function will be described below with reference to Figure 1.

[0031] <Configuration of the ADF system for image reading devices> The image reading device 11 shown in Figure 1 includes an automatic paper feeder 24. The automatic paper feeder 24 is configured to automatically feed the original document M1. The automatic paper feeder 24 is attached to the document cover 15. The automatic paper feeder 24 feeds the original document M1 into the document cover 15. A transport path 25 is formed in the document cover 15. The transport path 25 is the path through which the original document M1 is transported. The transport path 25 extends inside the document cover 15. The original document M1 is read by the image reading device 11 as it is transported along the transport path 25.

[0032] The automatic paper feeder 24 has a supply tray 26. The supply tray 26 is attached to the document cover 15. The supply tray 26 extends from the document cover 15. The supply tray 26 is configured to hold a document M1. The document M1 is set in the supply tray 26 when it is placed on the supply tray 26.

[0033] The automatic paper feeder 24 has a transport unit 30. The transport unit 30 is attached to the document cover 15. The transport unit 30 is configured to transport documents M1. The transport unit 30 transports documents M1 set in the supply tray 26 along a transport path 25. The transport unit 30 has one or more rollers. For example, the transport unit 30 has a pick roller 31 and one or more transport rollers 32. The pick roller 31 transports documents M1 set in the supply tray 26 one by one. In one example, the pick roller 31 contacts the uppermost document M1 among the multiple documents M1 stacked in the supply tray 26 and transports them in order from the uppermost document M1. The multiple transport rollers 32 are positioned along the transport path 25. The multiple transport rollers 32 transport documents M1 along the transport path 25.

[0034] The automatic paper feeder 24 has an output tray 33. The output tray 33 is configured to receive documents M1 ejected from the document cover 15. The output tray 33 is attached to the document cover 15. The output tray 33 receives scanned documents M1.

[0035] The automatic paper feeder 24 has a detection unit 34 that detects the presence or absence of a document M1 set in the supply tray 26. The detection unit 34 may be a contact-type sensor or a non-contact sensor such as an optical sensor.

[0036] The automatic paper feeder 24 may have a double-feed detection unit 35 that detects double feeding of documents M1. The double-feed detection unit 35 detects whether multiple documents M1 are being transported from the supply tray 26 while overlapping. The double-feed detection unit 35 may include an ultrasonic sensor. For example, the double-feed detection unit 35 detects a double feed when the attenuation rate of ultrasonic waves transmitted through the documents M1 exceeds a threshold.

[0037] The image reading device 11 comprises a reading unit 37 and a light-emitting unit 38. The reading unit 37 and the light-emitting unit 38 are supported by a support unit 39. The reading unit 37 and the light-emitting unit 38 constitute a reading module 40. The support unit 39 supports the reading module 40 in a position that allows it to read the original document M1 being transported along the transport path 25. The configuration of the reading module 40 is basically the same as that of the reading module 20 in the document tray 12. The transport unit 30, the second reading unit 37, and the light-emitting unit 38, which constitute the ADF-type image reading mechanism, are controlled by a control unit 50.

[0038] The reading unit 37 is positioned within the document cover 15 along the transport path 25. The reading unit 37 reads the document M1 being transported from the supply tray 26. In other words, the reading unit 37 reads the document M1 being transported along the transport path 25.

[0039] The light-emitting unit 38 can be switched on and off. The light-emitting unit 38 is positioned along the transport path 25. When the light-emitting unit 38 is lit, it illuminates the area of ​​the original document M1 being transported along the transport path 25 that includes the portion to be read by the reading unit 37.

[0040] The reading units 17 and 37 are configured to read both the front and back surfaces of the original document M1 as it is transported along the transport path 25. The reading unit 17 located within the document tray 12 combines the image reading functions of both the FB method and the ADF method. In this specification, the reading unit 17 within the document tray 12 is referred to as the "first reading unit 17," and the reading unit 37 within the automatic paper feeder 24 is also referred to as the "second reading unit 37."

[0041] The first reading unit 17 reads the first surface of the document M1 as it is transported along the transport path 25, through the reading window 21. At this time, the first reading unit 17 does not scan the document M1. The first reading unit 17 is positioned at a window position opposite the reading window 21 and reads the first surface of the document M1 through the reading window 21. The first surface of the document M1 is, for example, the front surface.

[0042] The second reading unit 37 reads the second side of the document M1 as it is transported along the transport path 25. The second side of the document M1 is the side opposite to the first side. For example, the second side of the document M1 is the back side.

[0043] When reading one side of the document M1 being transported along the transport path 25, it is read by the first reading unit 17. When reading both sides of the document M1 being transported along the transport path 25, it is read by both the first reading unit 17 and the second reading unit 37. That is, the first reading unit 17 reads the first side (for example, the front) of the document M1 through the reading window 21, and the second reading unit 37 reads the second side (for example, the back) of the document M1.

[0044] <About the document placement detection device> The image reading device 11 may read a thick document M1, such as a book or booklet (hereinafter also referred to as "books, etc."). For example, the user opens book B1 (see Figures 2 and 3) to the page they want to read and presses the open page onto the mounting surface 12A. Because book B1 is thick, the document cover 15 cannot be closed. Also, if the user tries to press the open page of book B1 against the transparent plate 14 while closing the document cover 15, a diagonal force is applied from the document cover 15 to book B1. As a result, the position of book B1 on the mounting surface 12A is likely to shift. Therefore, the pages of book B1 are read with the document cover 15 half-open. The user performs the reading operation while holding book B1 with their hand.

[0045] In the image reading device 11 of this embodiment, the control unit 50 detects, using the reading unit 17, that a document M1 such as a book has been placed on the placement surface 12A. In other words, the control unit 50 uses the reading unit 17 to detect the presence or absence of a document M1 such as a book on the placement surface 12A.

[0046] For example, the technology disclosed in Patent Document 1 detects the presence or absence of a document based on the results of two reading operations: one with the light-emitting unit turned off when the document cover is open before being lowered, and another with the light-emitting unit turned on when the document cover is closed during the process of lowering it. However, this conventional document detection technology requires the operation of lowering and closing the document cover, and the power consumption increases due to the illumination of the light-emitting unit. In contrast, the image reading device 11 of this embodiment is equipped with a document placement detection device that detects when the user has placed a document M1 on the placement surface 12A while the document cover 15 is open. This document placement detection device detects the presence or absence of a document M1 on the placement surface 12A using the reading unit 17 while suppressing the increase in power consumption associated with the illumination of the light-emitting unit 18 while the document cover 15 is open. Details of the document placement detection device will be described later.

[0047] <Configuration of the flatbed type image reading device 11> The configuration of the image reading device 11 will be explained with reference to Figures 2 and 3. Note that some components of the sheet-feed system, including the automatic paper feeder 24, are omitted in Figures 2 and 3. In Figures 2 and 3, the original document M1 is, for example, a document with thickness, such as a book or booklet. Figures 2 and 3 show a book B1 with the pages to be read open, placed on the mounting surface 12A. In other words, it shows the state in which the user has set the book B1 on the document tray 12 in order to read the pages of the book B1.

[0048] As shown in Figure 2, the document tray 12 has a rectangular shape when viewed from above. The lower surface 15A of the document cover 15 is a rectangle of approximately the same size as the upper surface of the document tray 12. The upper surface of the document tray 12 and the lower surface 15A of the document cover 15 are approximately the same in shape and size. In the closed state of the document cover 15 shown in Figure 1, the document tray 12 and the document cover 15 overlap in the vertical direction Z. In other words, in the closed state of the document cover 15, the document cover 15 covers the entire upper surface of the document tray 12, including the mounting surface 12A and the reading window 21.

[0049] As shown in Figures 2 and 3, when a document M1, such as a book B1, is placed on the mounting surface 12A of the document glass 12, the document cover 15 is opened to a predetermined angle. The document M1 is set on the mounting surface 12A of the transparent plate 14, for example, with the back and left edges facing each other. In the plan view shown in Figure 2, the document M1, such as a book B1, set on the mounting surface 12A protrudes slightly in front of the user (towards the +X side) from the open document cover 15. In particular, the user sets the document M1, such as a book B1, on the mounting surface 12A with the document cover 15 open to a relatively large degree. Therefore, when a user sets a standard-sized document M1, such as a book B1, on the mounting surface 12A, in most cases, a part of the document M1 protrudes slightly towards the +X side from the open document cover 15 in a plan view.

[0050] As shown in Figure 3, the image reading device 11 includes a scanning mechanism 44 that scans the carriage 19 in the sub-scanning direction Y, and a carriage motor 43 that is the drive source for the carriage 19, both located within the housing 13 of the document table 12. The carriage 19 moves in the sub-scanning direction Y via the scanning mechanism 44 due to the driving force of the carriage motor 43.

[0051] The scanning mechanism 44 includes a guide member 45 and a power transmission mechanism 46. The guide member 45 guides the carriage 19 so that it can move in the sub-scanning direction Y. The power transmission mechanism 46 transmits the driving force of the carriage motor 43 to the carriage 19 as power to move the carriage 19 in the sub-scanning direction Y. When the carriage motor 43 is driven forward, the carriage 19 moves in the first direction +Y, and when the carriage motor 43 is driven backward, the carriage 19 moves in the second direction -Y, which is the opposite direction to the first direction. Along with the movement of the carriage 19, the reading unit 17 and the light-emitting unit 18 that constitute the reading module 20 move in the sub-scanning direction Y.

[0052] In Figure 3, the position of the reading unit 17, shown by the solid line, is the standby position. The standby position is where the reading unit 17 faces the light-shielding portion between the reading window 21 and the transparent plate 14. When not performing readings, the reading unit 17 remains in the standby position.

[0053] When reading using the sheet-feed (SF) method, the reading unit 17 moves to a first reading position Y1 located at one end of the sub-scanning direction Y. The first reading position Y1 is the position in the sub-scanning direction Y where the reading unit 17 faces the reading window 21. In this embodiment, this position is also referred to as the "window position Y1".

[0054] When reading using the flatbed (FB) method, the reading unit 17 moves to a position within the document reading area SA in the sub-scanning direction Y. The document reading area SA is the area corresponding to the mounting surface 12A. The document reading area SA is the area from the base end Y0 to the end YE of the mounting surface 12A in the sub-scanning direction Y. The end YM of the document M1, such as this B1, in the sub-scanning direction Y is located at the same point as or -Y side of the end YE of the mounting surface 12A. The reading unit 17 reads the document M1, such as this B1, placed on the mounting surface 12A by scanning within the document reading area SA in the sub-scanning direction Y from the standby position shown in Figure 3. The reading unit 17 reads the document M1 by receiving the reflected light that is reflected from the surface of the document M1 being read by the light emitted from the light-emitting unit 18.

[0055] In this embodiment, when detecting the placement of a document, the reading unit 17 performs readings at two positions: the window position Y1 and the second reading position Y2, which is a position within the document reading area SA. The second reading position Y2 can be any position within the document reading area SA where there is a high probability that a document M1, such as a standard-sized book B1, will be placed. An example of a position where a document M1, such as a standard-sized book B1, may be placed is, for example, a position within 200 mm from the base end Y0. In order to shorten the travel time for the reading unit 17 to move from the first reading position Y1 (window position Y1) to the second reading position Y2 during the document placement detection process, the second reading position Y2 may be, for example, a position within 100 mm from the base end Y0.

[0056] <Configuration of reading unit 20> Next, with reference to Figure 4, the configuration of the reading module 20 will be described. The two reading modules 20 and 40 have the same basic configuration. Therefore, the configuration of the reading module 20 will be described below.

[0057] The reading module 20 has an elongated support portion 27 that extends in the main scanning direction X. The reading module 20 has a reading unit 17 and a light-emitting unit 18. The reading unit 17 and the light-emitting unit 18 are supported by the support portion 27 in a configuration in which their longitudinal directions coincide with the main scanning direction X.

[0058] As shown in Figure 4, the reading unit 17 is composed of, for example, a line sensor 17L. The reading unit 17, consisting of the line sensor 17L, includes a plurality of image sensors 28 arranged in a row along the main scanning direction X. The image sensors 28 are photoelectric conversion elements. Each image sensor 28 corresponds to one reading pixel (1 pixel) that makes up the line sensor 17L. The reading unit 17 is composed of m image sensors 28 arranged in a row along the main scanning direction X. m is, for example, a predetermined number in the range of 500 to 10000. The reading unit 17 includes a plurality of image sensors 28. The plurality of image sensors 28 output a brightness signal corresponding to the incident light.

[0059] The light-emitting units 18 are arranged one at one end of the support unit 27 in the longitudinal direction, or two at both ends. In the example shown in Figure 4, two light-emitting units 18 are arranged at both ends of the support unit 27 in the longitudinal direction. The support unit 27 includes a light guide member 29 that can guide the light from the light-emitting units 18 when lit in the main scanning direction X and irradiate the area to be read. The light guide member 29 is, for example, a light guide. The light-emitting units 18 may be a white light source that emits white light, or they may be configured to have three types of light sources that can emit monochromatic light of red, green, and blue, respectively. The light-emitting units 18 may be, for example, made of light-emitting LEDs.

[0060] The light guide members 29 are provided in pairs on both sides of the reading unit 17, which consists of line sensors 17L, in the sub-scanning direction Y. The light guide members 29 guide light from the light-emitting unit 18 in the main scanning direction X, thereby emitting light from the guided light path. The light emitted by the light guide members 29 illuminates the area to be read by the reading unit 17. The reading module 20 is equipped with a lens (not shown) that focuses light onto the line sensors 17L that constitute the reading unit 17. The lens may be composed of, for example, a lens array having one lens section for each image sensor 28.

[0061] <Electrical configuration of image reading device 11> Next, the electrical configuration of the image reading device 11 in this embodiment will be described with reference to Figure 5. Note that in Figure 5, some of the components of the ADF-type image reading mechanism of the image reading device 11, which are less related to the document placement detection device, have been omitted.

[0062] As shown in Figure 5, the image reading device 11 includes a control unit 50, a carriage motor 43, a reading unit 17, a light-emitting unit 18, an open / close sensor 23, and a display unit 41. The control unit 50 may consist of one or more processors that perform various processes according to a computer program. The control unit 50 may consist of one or more dedicated hardware circuits, such as ASICs, that perform at least some of the various processes. The control unit 50 may consist of a circuit that includes a combination of processors and hardware circuits. The processor includes a CPU and memory 52 such as RAM and ROM. Memory 52 stores program code or instructions configured to cause the CPU to perform processes. Memory, i.e., computer-readable media, includes any readable media that can be accessed by a general-purpose or dedicated computer.

[0063] The control unit 50 is electrically connected to the carriage motor 43, reading unit 17, light-emitting unit 18, opening / closing sensor 23, and display unit 41. The control unit 50 controls the carriage motor 43, reading unit 17, and light-emitting unit 18 to read the document M1 and perform document placement detection processing to detect that the document M1 has been placed on the placement surface 12A.

[0064] The control unit 50 includes an image reading control unit 51 and a memory 52. ​​The memory 52 stores a control program PR and threshold data D1. The image reading control unit 51 consists of software, which is configured by the computer of the control unit 50 executing the control program PR, etc., and hardware such as an ASIC. The image reading control unit 51 includes a carriage drive control unit 61, a reading control unit 62, a light emission control unit 63, a cover opening / closing determination unit 64, a display control unit 65, a first determination unit 66, and a second determination unit 67. The threshold data D1 includes various data such as threshold values ​​used by the first determination unit 66 and the second determination unit 67 for determination. The threshold data D1 includes, for example, a first threshold A1 used by the first determination unit 66 for determination, and a second threshold A2 used by the second determination unit 67 for determination. The first threshold A1 and the second threshold A2 are set to values ​​obtained through preliminary experiments and simulations so that the first determination unit 66 and the second determination unit 67 can make appropriate determinations.

[0065] The carriage drive control unit 61 controls the carriage motor 43. The carriage drive control unit 61 moves the carriage 19 in the sub-scanning direction Y by driving the carriage motor 43 in forward and reverse directions. The control unit 50 scans the reading unit 17 and the light-emitting unit 18 in the sub-scanning direction Y as a result of the movement of the carriage 19.

[0066] The reading control unit 62 controls the reading unit 17. The reading control unit 62 controls the reading operation of the reading unit 17. The reading unit 17 outputs a reading signal consisting of an analog signal by reading the original document M1. The control unit 50 generates reading data by converting the reading signal input from the reading unit 17 from an analog signal to a digital signal. The control unit 50 generates image data, which is the reading result of the original document M1, by applying predetermined processing to the reading data.

[0067] The light emission control unit 63 controls the switching between illumination and extinguishing of the light emission unit 18. The control unit 50 extinguishes the light emission unit 18 when in standby mode and not performing scanning. The control unit 50 illuminates the light emission unit 18 while scanning the document M1. The control unit 50 extinguishes the light emission unit 18 during the document placement detection process, which detects that the document M1 has been placed on the placement surface 12A.

[0068] The cover opening / closing determination unit 64 receives the detection signal from the opening / closing sensor 23. Based on the detection signal received from the opening / closing sensor 23, the cover opening / closing determination unit 64 determines whether the document cover 15 is open or closed. Here, the opening / closing sensor 23 outputs a detection signal (ON signal) when the document cover 15 is closed, and outputs a non-detection signal (OFF signal) when the document cover 15 is open. The opening / closing sensor 23 outputs a non-detection signal indicating the open state when the angle of the document cover 15 exceeds a predetermined angle greater than 0 degrees. The opening / closing sensor 23 outputs a detection signal indicating the closed state when the angle of the document cover 15 is less than the predetermined angle.

[0069] The display control unit 65 controls the display unit 41. By controlling the display unit 41, the display control unit 65 displays information on the screen of the display unit 41 and switches the information displayed on the screen. The display control unit 65 informs the user of information by displaying it on the display unit 41. When the user is in a mode for scanning thick documents such as book B1 (book scan mode), the display control unit 65 displays guidance information on the display unit 41. If the display unit 41 is a touch panel, the control unit 50 receives input information entered by the user via touch operation from the operation unit 42 that constitutes the display unit 41.

[0070] The first determination unit 66 performs a first determination to determine whether or not it can detect the document M1 placed on the placement surface 12A, based on the first reading result, which is the reading result of the first reading process described later and which constitutes the document placement detection process.

[0071] The second determination unit 67 performs a second determination to determine whether or not the document M1 has been placed on the placement surface 12A, based on the difference between the second reading result, which is the reading result of the second reading process described later and constitutes the document placement detection process, and the first reading result.

[0072] <About the document placement detection process> Next, with reference to Figures 1 to 3 and 6 to 9, the document placement detection process for detecting that a document M1 has been placed on the placement surface 12A will be described. The document placement detection process includes a first reading process and a second reading process. The first reading process is a reading process for obtaining a first reading result used in the first determination to determine whether or not it is possible to detect that a document M1 has been placed on the placement surface 12A. The control unit 50 executes the second reading process when the first determination unit 66 determines that detection is possible. The control unit 50 detects whether or not a document M1 has been placed on the placement surface 12A based on the second reading result, which is the reading result of the second reading process, and the first reading result, which is the reading result of the first reading process. This detection is performed by a second determination by the second determination unit 67. In other words, the control unit 50 detects the presence or absence of the document M1 on the placement surface 12A by performing a second determination, in which the second determination unit 67 determines whether or not the document M1 has been placed on the placement surface 12A based on the first reading result and the second reading result.

[0073] Figure 6 is an explanatory diagram of the first reading process. Figure 7 is an explanatory diagram of the second reading process. Figure 8 is a graph showing the first reading result and the second reading result. Figure 9 is a graph showing the difference data between the first reading result and the second reading result. Hereinafter, each process constituting the document placement detection process will be explained in order with reference to Figures 6 to 9.

[0074] <Regarding the first reading process> First, the first reading process and the first determination will be explained with reference to Figures 1 to 3 and Figure 6. The control unit 50 performs a first reading process in which it causes the reading unit 17 to perform reading with the light-emitting unit 18 turned off, before the document cover 15 is in the open state and the document M1 is placed on the placement surface 12A. The control unit 50 performs the first reading process based on the result of the open / close sensor 23 detecting the open state of the document cover 15. The control unit 50 performs the first reading process with the reading unit 17 facing the reading window 21.

[0075] The control unit 50 performs a first determination to determine whether or not it can detect the original document M1 placed on the mounting surface 12A, based on the first reading result, which is the reading result of the first reading process. Specifically, the first determination unit 66 of the control unit 50 performs the first determination.

[0076] The control unit 50 receives brightness signals corresponding to the incident light from the multiple image sensors 28 that constitute the reading unit 17. Based on the brightness signals received from the multiple image sensors 28 that constitute the reading unit 17, the control unit 50 generates digital reading data (see Figure 6).

[0077] The graph shown in Figure 6 shows the first reading result SD1. The horizontal axis of this graph represents the main scanning position, and the vertical axis represents the read data value. Here, the main scanning position is the pixel position indicating the position in the main scanning direction X of the multiple (m) image sensors 28 that constitute the reading unit 17. The read data value represents the luminance value corresponding to the signal value when the luminance signals input from the multiple image sensors 28 are converted into digital signals of a predetermined gradation (for example, 256 gradations). The first reading result SD1 corresponds to the luminance value expressed in 256 gradations. In the first determination, the control unit 50 determines that the original document M1 can be detected if there is a luminance signal in the luminance signal of the first reading result that exceeds the first threshold A1. That is, the first determination unit 66 of the control unit 50 determines whether or not there is data in the first reading result SD1 that exceeds the first threshold A1 in the graph shown in the lower part of Figure 6.

[0078] Figure 6 shows the state with the document cover 15 open and before the document M1 is placed on it. In the room where the image reading device 11 is placed, an illumination unit 70 is installed at a predetermined height above the image reading device 11. The illumination unit 70 illuminates the image reading device 11 from a predetermined direction. In the example shown in Figure 6, the illumination unit 70 is located almost directly above the image reading device 11. The ambient light L from the illumination unit 70 is irradiated onto the image reading device 11 in a direction such as the vertical Z.

[0079] The rotating end 15B of the document cover 15 rotates in an arc trajectory when the document cover 15 is opened and closed. As a result, a shadow is cast on the area where the open document cover 15 shown in Figure 6 is projected in the illumination direction (for example, the vertical direction Z), and a bright area LA illuminated by ambient light L is formed on the +X side of the main scanning direction X from the dark area CS formed by the shadow. The position X1 of the boundary between the dark area CS and the bright area LA is displaced in the main scanning direction X according to the opening angle of the document cover 15. The rising position X1 of the first reading result SD1 in the graph shown in Figure 6 corresponds to the boundary between the dark area CS and the bright area LA. If the light intensity in the bright area LA exceeds the first threshold A1, it is possible to detect that the document M1 has been placed on the placement surface 12A using ambient light L.

[0080] As shown in Figure 6, when the document cover 15 is open before the document M1 is placed on the placement surface 12A, the reading unit 17 detects ambient light L that is not blocked by the document cover 15. If the light intensity of the ambient light L illuminating the placement surface 12A is above a certain level, as shown in Figure 6, there is data in the reading data of the first reading result SD1 that exceeds the first threshold A1. In this case, the first determination unit 66 determines that there is data in the first reading result SD1 that exceeds the first threshold A1. On the other hand, when the document cover 15 is closed (Figure 1) or when the light intensity of the ambient light L shown in Figure 6 is weak, the first reading result SD0, shown by the dashed line in the graph of Figure 6, is obtained. There is no data in the reading data of this first reading result SD0 that exceeds the first threshold A1. In this case, the first determination unit 66 determines that the presence or absence of the document M1 on the placement surface 12A cannot be detected.

[0081] <Regarding the second reading process> Next, the second reading process will be explained with reference to Figures 1 to 3 and Figure 7. The control unit 50 executes a second reading process if the result of the first determination indicates that detection is possible. Specifically, the control unit 50 executes a second reading process in which the reading unit 17 performs reading with the document cover 15 open and the light-emitting unit 18 turned off.

[0082] Figure 7 shows the state when the document cover 15 is open and the document M1 is placed on the mounting surface 12A. The position of the rotating end 15B of the document cover 15 is the same as in Figure 6. When the document M1, which consists of the book B1 shown by the solid line in Figure 7, is placed on the mounting surface 12A, the book B1 blocks the ambient light L, creating a dark area MS due to the shadow of the book B1. The position X2 of the boundary between the dark area MS and the light area LA with the book B1 in place corresponds to the position ME of the +X side end face of the book B1. If the book B1 is of a typical size, in most cases the second position X2 is located +X side more than the first position X1. In other words, a part of the shadow of the book B1 placed on the mounting surface 12A extends +X side from the boundary position X1 of the dark area CS, which is the shadow area of ​​the document cover 15. The shadow of the part of the book B1 that extends +X side from the first position X1 changes the area into a dark area.

[0083] The graph shown in Figure 7 shows the second reading result SD2. The horizontal axis of this graph represents the main scanning position, and the vertical axis represents the read data value. The read data value corresponds to the luminance value expressed in 256 levels of brightness for the luminance signal of the second reading result. In the graph shown in Figure 7, the rising edge position X2 of the second reading result SD2 corresponds to the boundary between the dark region MS, which is the shadow of the book B1, and the bright region LA, which is created when ambient light L illuminates a part of the mounting surface 12A. In other words, the rising edge position X2 corresponds to the +X side end face ME of the book B1 placed on the mounting surface 12A. Here, when a book B1 of a general size is placed on the mounting surface 12A, the position of the end face ME of the book B1 is located +X side more than the first position X1. In other words, the second reading result SD2 rises at position X2 which is +X side more than the rising edge position X1 in the first reading result SD1 (see Figure 6).

[0084] Note that when a book B1 smaller than the standard size shown by the dashed line in Figure 7 is placed on the document, or when the opening angle of the document cover 15 is considerably narrower than the angle at which it can normally be opened, the position of the +X side edge ME of the book B1 will be the same as the position X1 of the boundary between the dark area and the light area formed by the shadow of the document cover 15, or it will be on the -X side. Except for such rare cases, in most cases the second position X2 will be on the +X side of the first position X1 (X1 <X2)。

[0085] <Regarding the second decision> Next, the second determination will be explained with reference to Figures 8 and 9. The control unit 50 performs a second determination to determine whether or not the original document M1 has been placed on the mounting surface 12A, based on the first reading result SD1 and the second reading result SD2. That is, the control unit 50 detects that the original document M1 has been placed on the mounting surface 12A based on the difference between the first reading result obtained by the first reading process and the second reading result obtained by the second reading process. The control unit 50 performs a second determination to determine whether or not the original document M1 has been placed on the mounting surface 12A, based on the difference between the second reading result and the first reading result. In the second determination, the control unit 50 determines that the original document M1 has been placed on the mounting surface 12A if there is difference data ΔL that exceeds the second threshold A2 among the difference data indicating the difference between the brightness signal in the first reading result and the brightness signal in the second reading result. This second determination is performed by the second determination unit 67 of the control unit 50.

[0086] Figure 8 is a graph comparing the first reading result SD1 and the second reading result SD2. The horizontal and vertical axes of this graph are the same as in Figures 6 and 7. That is, the horizontal axis is the main scanning position, and the vertical axis is the reading data value indicating the brightness value. The second position X2, which is the rising edge position of the second reading result SD2, is located +X side more than the first position X1, which is the rising edge position of the first reading result SD1. The hatched area shown in Figure 8 shows the difference ΔL between the first reading result SD1 and the second reading result SD2. The difference ΔL is large in the region between the first position X1 and the second position X2 at the main scanning position. This is due to the following reason: Before the B1 is placed, ambient light L that is not blocked by the open document cover 15 is irradiated onto the placement surface 12A, creating a bright area on the placement surface 12A in the region +X side of the first position X1. When the book B1 is placed on the mounting surface 12A, a portion of the bright area of ​​the book B1 before placement changes into a dark area due to the shadow cast by the portion of the book B1 that extends beyond the first position X1 to the +X side. In other words, the area between the first position X1 and the second position X2 changes from a bright area to a dark area. As a result, the difference ΔL between the first reading result SD1 and the second reading result SD2 becomes larger in the area between the first position X1 and the second position X2.

[0087] The second determination unit 67 calculates the difference data ΔL, which is the difference between the first reading result SD1 and the second reading result SD2. The second determination unit 67 calculates the difference data ΔL by subtracting the second reading result SD2 from the first reading result SD1 (ΔL = SD1 - SD2). The difference data ΔL may also be the absolute value of the subtraction between the first reading result SD1 and the second reading result SD2 (ΔL = |SD1 - SD2|).

[0088] The second determination unit 67 determines whether or not there is any data in the difference data ΔL that exceeds the second threshold A2. If the main B1 is not placed on the mounting surface 12A, the second reading result SD2, shown by the dashed line in the graph shown in Figure 7, is obtained. This second reading result SD2 rises at the same first position X1 as the first reading result SD1, shown by the dashed line in the graph shown in Figure 6. Therefore, there is no significant difference between the first reading result SD1 and the second reading result SD2. In this case, the second determination unit 67 determines that there is no data in the difference data ΔL that exceeds the second threshold A2.

[0089] On the other hand, when the book B1 is placed on the placement surface 12A, a second reading result SD2 indicated by a solid line in the graph shown in FIG. 7 is obtained. This second reading result SD2 rises at a second position X2 (>X1) different from the first position X1, which is the rising position of the first reading result SD1 indicated by a dashed-dotted line in the graph shown in FIG. 6. Therefore, a significant difference occurs between the first reading result SD1 and the second reading result SD2. The second determination unit 67 determines that there is data exceeding the second threshold value A2 among the difference data ΔL between the first reading result SD1 and the second reading result SD2. When the determination result that there is data satisfying ΔL>A2 is obtained, the second determination unit 67 detects that the document M1 is placed on the placement surface 12A. If each of the positions X1 and X2, which are the projection positions in the irradiation direction of the external light L between the rotation end 15B of the document cover 15 and the end face ME of the book B1, does not satisfy X1<X2, there is no data exceeding the second threshold value A2 in the difference data ΔL. Also, when the position of the end face ME of the book B1 is located on the -X side in the main scanning direction X with respect to the first position X1 of the rotation end 15B of the document cover 15, as in the case of the small-sized book B1 indicated by a two-dot chain line in FIG. 7, there is no data exceeding the second threshold value A2 in the difference data ΔL.

[0090] <Regarding the third reading process> When the result of the first determination is negative and the document M1 cannot be detected by the second determination, the control unit 50 executes a third reading process in which the reading unit 17 is made to perform reading with the document cover 15 in the open state and the light emitting unit 18 lit. The third reading process may include reading (reading process A) with the document cover 15 in the open state and the light emitting unit 18 turned off. The third reading process may include reading (reading process B) with the document cover 15 in the open state and the light emitting unit 18 lit. The third reading process may include reading (reading process C) with the document cover 15 in the closed state and the light emitting unit 18 lit.

[0091] Furthermore, the third reading process may include reading with the document cover 15 open and the light-emitting unit 18 turned off (reading process A), and reading with the document cover 15 open and the light-emitting unit 18 turned on (reading process B). In this case, the control unit 50 detects that the document M1 has been placed on the placement surface 12A based on the difference between the reading result of reading process A and the reading result of reading process B, by detecting that there is data where the difference data exceeds a threshold.

[0092] Furthermore, the third reading process may include reading with the document cover 15 open and the light-emitting unit 18 turned off (reading process A), reading with the document cover 15 open and the light-emitting unit 18 turned on (reading process B), and reading with the document cover 15 closed and the light-emitting unit 18 turned on (reading process C). In this case as well, the control unit 50 detects that a document M1 has been placed on the placement surface 12A when there is data where the difference data between the reading result of reading process A and the reading result of reading process B exceeds a threshold. If a black document M1 is placed on the placement surface 12A, the difference data between the reading result of reading process A and the reading result of reading process B does not exceed a threshold, so the presence or absence of document M1 cannot be detected. However, the control unit 50 may detect the presence or absence of a black document M1 based on the difference data and the reading result of reading process C. In other words, the control unit 50 determines that the original document M1 is placed on the placement surface 12A if the difference data is less than the threshold and the reading result of reading process C is less than the threshold. On the other hand, the control unit 50 determines that the original document M1 is not placed on the placement surface 12A if the difference data is less than the threshold and the reading result of reading process C is greater than or equal to the threshold. This determination also allows the presence or absence of a black original document M1 to be detected based on the reading result of the third reading process.

[0093] <Regarding manuscript scanning processing> Next, the document reading process will be described. Based on the detection that the document M1 has been placed on the placement surface 12A, the control unit 50 executes a document reading process instructing the reading unit 17 to read the document M1. The control unit 50 executes the document reading process if the result of the second determination indicates that the document has been placed. The control unit 50 executes the document reading process with the document cover 15 open. The control unit 50 controls the carriage motor 43 to move the carriage 19 along the placement surface 12A in the sub-scanning direction Y, thereby moving the document reading area SA. While the carriage 19 is moving, the control unit 50 lights up the light-emitting unit 18 and instructs the reading unit 17 to read the document M1 through the transparent plate 14. The reading unit 17 reads the document M1 by receiving the reflected light that is reflected off the document M1 from the light emitted by the light-emitting unit 18. The control unit 50 generates image data based on the reading data read by the document reading process. The control unit 50 may perform a cropping process to cut out the portion of page B1 to be read from the image data. The control unit 50 may generate a file in a specified file format based on the image data. The file may include, for example, one of the following: a PDF file, a JPEG file, or a TIFF file.

[0094] <Operation of the Embodiment> Next, the operation of the image reading device 11 will be explained with reference to Figure 10, etc. The document reading control routine shown in Figure 10, which is executed by the control unit 50, will be described below. This document reading control routine includes document placement detection processing. The user selects document reading (scanning), reading conditions, and a document reading mode including document placement detection processing (e.g., book scan mode) by operating the touch panel of the display unit 41. The user instructs the image reading device 11 to read the document M1 by performing an operation to instruct the reading to be executed. Upon receiving the user's instruction to execute reading, the control unit 50 executes the document reading control routine shown in Figure 10 if the instructed mode is a document reading mode including document placement detection processing.

[0095] First, in step S11, the control unit 50 determines whether or not the open state of the document cover 15 has been detected. If the open state of the document cover 15 is detected, the process proceeds to step S12. On the other hand, if the open state of the document cover 15 is not detected, that is, if the closed state of the document cover 15 is detected, the control unit 50 waits for the document cover 15 to be detected to proceed.

[0096] In step S12, the control unit 50 reads the first threshold A1 and the second threshold A2. In step S13, the control unit 50 moves the carriage 19 to window position Y1. As shown in Figures 1 to 3, the carriage 19 moves to window position Y1 opposite the reading window 21.

[0097] In the next step S14, the control unit 50 performs a first reading process at window position Y1. The control unit 50 performs a first reading process with the light-emitting unit 18 turned off and the reading unit 17 performing the reading while the document cover 15 is open and before the document M1 is placed on the placement surface 12A. By performing the first reading process at window position Y1, it is possible to avoid, for example, performing the first reading process while the document M1 or the like is placed on the placement surface 12A. If the configuration is set to perform the first reading process in the document reading area SA, it is possible that the first reading process will be performed while the document M1 or the like is placed on the placement surface 12A. In such a case, it is not possible to perform the first determination accurately. Therefore, in this embodiment, a configuration is adopted in which the first reading process is performed at window position Y1.

[0098] In step S15, the control unit 50 determines whether or not there is data in the first reading result that exceeds the first threshold A1. This determination process corresponds to the first determination performed by the first determination unit 66. As shown in Figure 6, when the document cover 15 is open before the document M1 is placed on the placement surface 12A, the reading unit 17 detects ambient light L that is not blocked by the document cover 15, and there is data in the reading data that exceeds the first threshold A1. In this case, the control unit 50 determines that there is data in the first reading result that exceeds the first threshold A1. On the other hand, as shown in Figure 1, when the document cover 15 is closed, or when the light intensity of ambient light L as shown in Figure 6 is weak, there is no data in the reading data that exceeds the first threshold A1. In this case, the control unit 50 determines that there is no data in the first reading result that exceeds the first threshold A1. If there is data that exceeds the first threshold A1, the control unit 50 proceeds to step S16, and if there is no data that exceeds the first threshold A1, it proceeds to step S21.

[0099] In the next step S16, the control unit 50 moves the carriage to the document reading area SA. As a result, the carriage 19 moves to the position shown by the dashed line in Figure 1 within the document reading area SA.

[0100] The destination position of the carriage 19 at this time can be anywhere within the document scanning area SA. For example, when the document B1 is opened and placed on the scanner, the central part corresponding to the back of the document B1 tends to lift up. Therefore, there is a possibility that ambient light L may enter below the document B1 around the central part of the document B1. For this reason, the position corresponding to the back of the document B1 may be avoided. The destination position of the carriage 19 when it moves to the document scanning area SA can be anywhere within a predetermined range, for example, from the base end Y0 to a position corresponding to half the width dimension of the document B1 in the sub-scanning direction Y. In addition, since the document B1 may not be placed in the vicinity of the base end Y0, the destination position of the carriage 19 can be anywhere from a position slightly (for example, 10 mm) displaced from the base end Y0 towards the +Y side of the sub-scanning direction Y to a predetermined distance (for example, 100 mm).

[0101] In step S17, the control unit 50 executes a second reading process. The control unit 50 executes a second reading process in which the reading unit 17 performs a reading with the document cover 15 in the open state and the light-emitting unit 18 turned off. The control unit 50 determines whether the document cover 15 is in the open state based on the detection result of the open / close sensor 23. For example, if the user closes the document cover 15, the control unit 50 detects that the document cover 15 has become closed based on the detection result of the open / close sensor 23, and interrupts the second reading process and terminates the routine.

[0102] In step S18, the control unit 50 determines whether or not a timeout has occurred. After the carriage 19 moves to the document scanning area SA in step S16, the control unit 50 starts timing the elapsed time using a timer (not shown). If the user does not place the document B1 for more than the set time (timeout time), the control unit 50 declares that time is up. If it is not a timeout, the control unit 50 proceeds to step S19; if it is a timeout, it proceeds to step S22.

[0103] In step S19, the control unit 50 determines whether there is any data in the difference data ΔL between the first reading result and the second reading result that exceeds the second threshold A2. The control unit 50 calculates the difference between the first reading result SD1 and the second reading result SD2 shown in Figure 8. As a result of this calculation, the control unit 50 obtains the difference data ΔL shown in Figure 9. Then, the control unit 50 determines whether there is any data in the difference data ΔL shown in Figure 9 that exceeds the second threshold A2.

[0104] The position X1 where the first reading result SD1 rises in the graph shown in FIG. 6 corresponds to the projection position in the irradiation direction of the external light L of the rotation end 15B of the document cover 15. The second position X2 where the second reading result SD2 rises in the graph shown in FIG. 7 corresponds to the projection position in the irradiation direction of the external light L of the end face ME of the book B1 which is the document M1. Usually, since the book B1 placed on the placement surface 12A contacts the placement surface 12A, the second position X2 where the second reading result SD2 rises corresponds to the position of the end face ME of the book B1. Here, for each position X1 and X2 between the rotation end 15B of the document cover 15 and the end face ME of the book B1, when the book B1 is of a general size, in most cases, the second position X2 is larger than the first position X1 (X1 < X2). Therefore, when the book B1 is placed on the placement surface 12A, it is determined that there is data exceeding the second threshold value A2 among the difference data ΔL. When there is data exceeding the second threshold value A2 among the difference data ΔL, the control unit 50 detects that the document M1 is placed on the placement surface 12A. On the other hand, when the book B1 is not placed on the placement surface 12A, there is no significant difference from the first reading result SD1 shown by the dashed line in FIG. 6, like the second reading result SD2 shown by the dashed-dotted line in the graph shown in FIG. 7. That is, the difference data ΔL becomes 0 (zero) or a value near zero. In this case, the control unit 50 determines that there is no data exceeding the second threshold value A2 among the difference data ΔL.

[0105] If there is data exceeding the second threshold value A2, the control unit 50 proceeds to the process of step S20. On the other hand, if there is no data exceeding the second threshold value A2, the control unit 50 returns to the process of step S17. In this case, the control unit 50 repeats the processes of steps S17 to S19 until it determines that there is data exceeding the second threshold value A2 in step S19, that is, the document M1 is detected, or it determines timeout in step S18. In some exceptional cases, such as when the opening angle of the document cover 15 is much narrower than normal or when a small-sized book B1 shown by the dashed-dotted line in FIG. 7 is placed on the placement surface 12A, the control unit 50 determines that there is no data exceeding the second threshold value A2 among the difference data ΔL. Therefore, in these cases, a timeout occurs in step S18.

[0106] In the next step S20, the control unit 50 executes the document reading process. When the control unit 50 detects that the document M1 has been placed on the placement surface 12A based on the determination result in step S19, it executes the document reading process. With the light-emitting unit 18 lit, the control unit 50 moves the carriage 19 in the sub-scanning direction Y, causing the reading unit 17 to scan the document reading area SA. Through this scanning, the reading unit 17 moves in the sub-scanning direction Y while reading the area of ​​the document M1 to be read, illuminated by the lit light-emitting unit 18, through the transparent plate 14. The reading unit 17 performs the reading operation, for example, from the base end Y0 to a position past the end face ME. In this way, the control unit 50 executes the document reading process to read the document M1.

[0107] On the other hand, if the result of step S15 is NO, in step S21 the control unit 50 moves the carriage 19 to the document reading area SA. In other words, if it is determined in step S15 that there is no data exceeding the first threshold A1, in step S21 the control unit 50 moves the carriage 19 from the window position Y1 to the document reading area SA.

[0108] In the next step S22, the control unit 50 executes a third reading process. The third reading process is a reading process in which the light-emitting unit 18 is lit and the reading unit 17 performs the reading. The third reading process may include a reading process in which the light-emitting unit 18 is lit and the reading unit 17 performs the reading. The third reading process may include at least one of the reading processes A, B, and C described above. The third reading process may include both reading process A and reading process B. Furthermore, the third reading process may include reading process A, reading process B, and reading process C. If it is determined by each process from step S11 to step S19 that document detection without illuminating the light-emitting unit 18 is impossible or difficult, then each process from step S21 to step S23 executes a document detection process that involves illuminating the light-emitting unit 18. In the third reading process executed by the control unit 50 in step S22, when the original document M1 is placed on the placement surface 12A, the reading unit 17 receives the reflected light from the light-emitting unit 18 that illuminates the original document M1, so the brightness value of the read data increases in the main scanning position range corresponding to the area where the original document M1 is located.

[0109] In the next step S23, the control unit 50 determines whether or not a document has been detected. Based on the reading data obtained as the third reading result, which is the reading result of the third reading process, the control unit 50 determines whether or not the document M1 has been placed on the mounting surface 12A. The control unit 50 may, for example, determine whether or not there is data in the reading data that exceeds a threshold. The control unit 50 may also determine whether or not there is data in the difference data of multiple reading results that exceeds a threshold. Furthermore, in the third reading process, which includes reading process A, reading process B, and reading process C, the control unit 50 may determine whether or not the document M1 has been placed on the mounting surface 12A based on the respective reading results, for example, based on conditions that allow detection of a white or color document M1 and conditions that allow detection of a black document M1. When the conditions for determining that the document M1 has been placed on the mounting surface 12A are met, the control unit 50 determines that the document M1 has been placed on the mounting surface 12A. On the other hand, if the determination condition is not met, the control unit 50 determines that the original document M1 is not placed on the placement surface 12A. In this way, the control unit 50 detects the presence or absence of the original document M1. If the original document is detected, the control unit 50 proceeds to step S24; otherwise, it returns to the process in step S22. In this case, the control unit 50 repeats the processes in steps S22 and S23 until it determines in step S23 that the original document has been detected.

[0110] In step S24, the control unit 50 performs a document reading process. This document reading process is the same as the document reading process in step S20. With the light-emitting unit 18 lit, the control unit 50 causes the reading unit 17 to read the document.

[0111] Thus, in this embodiment, the system detects that the user has placed the document M1 on the placement surface 12A based on the reading result of the reading unit 17. The light-emitting unit 18 is not illuminated during this document detection. Therefore, it is possible to detect that the document M1 has been placed on the placement surface 12A using the reading result of the reading unit 17 while keeping power consumption low.

[0112] <Document detection method> The image reading device 11 of this embodiment comprises a document tray 12, a reading unit 17, a light-emitting unit 18, and a document cover 15. This image reading device 11 implements a document detection method for detecting a document M1 placed on the document tray 12. This document detection method comprises the following (A) to (C). (A) With the document cover 15 open and before the document M1 is placed on the placement surface 12A, a first reading process is performed in which the reading unit 17 is made to perform reading with the light-emitting unit 18 turned off. (B) If, based on the results of the first reading process, it is determined that the document M1 placed on the placement surface 12A can be detected, a second reading process is performed in which the reading unit 17 is instructed to perform reading with the document cover 15 open and the light-emitting unit 18 turned off. (C) Based on the difference between the result of the second reading process and the result of the first reading process, the document placed on the placement surface 12A is detected.

[0113] The above (A) corresponds to the processes in steps S11, S13, and S14 in the example shown in Figure 10. The above (B) corresponds to the processing in steps S15 to S17 in the example shown in Figure 10. The above (C) corresponds to the process in step S19 in the example shown in Figure 10.

[0114] <Manuscript reading method> In this embodiment, the document reading method for reading the document M1 placed on the document tray 12 with the image reading device 11 comprises the following (A) to (D). (A) With the document cover 15 open and before the document M1 is placed on the placement surface 12A, a first reading process is performed in which the reading unit 17 is made to perform reading with the light-emitting unit 18 turned off. (B) If, based on the results of the first reading process, it is determined that the document M1 placed on the placement surface 12A can be detected, a second reading process is performed in which the reading unit 17 is instructed to perform reading with the document cover 15 open and the light-emitting unit 18 turned off. (C) Based on the difference between the result of the second reading process and the result of the first reading process, it is detected that the original document M1 has been placed on the placement surface 12A. (D) Based on the detection that the document M1 has been placed on the placement surface 12A, the document reading process is executed, causing the reading unit 17 to read the document M1. In other words, the document reading method includes the document detection method described above (A) to (C) and (D). Each of (A) to (C) corresponds to the process indicated by the step number in Figure 10 in the document detection method. Furthermore, (D) corresponds to the process of step S20 in the example shown in Figure 10.

[0115] <Effects of the Embodiment> According to this embodiment, the following effects can be obtained. (1) The image reading device 11 comprises a document tray 12, a reading unit 17, a light-emitting unit 18, a document cover 15, and a control unit 50. The document tray 12 has a mounting surface 12A on which the document M1 is placed. The reading unit 17 reads the document M1 placed on the mounting surface 12A of the document tray 12 from the side opposite to the mounting surface 12A. The light-emitting unit 18 can be switched on and off, and when lit, it illuminates the document M1 from the side opposite to the mounting surface 12A of the document tray 12. The document cover 15 opens and closes the mounting surface 12A of the document tray 12. The control unit 50 performs a first reading process in which the reading unit 17 performs reading with the light-emitting unit 18 turned off when the document cover 15 is in the open state and before the document M1 is placed on the mounting surface 12A. The control unit 50 performs a second reading process, instructing the reading unit 17 to perform reading with the document cover 15 open and the light-emitting unit 18 turned off. Based on the difference between the first reading result obtained by the first reading process and the second reading result obtained by the second reading process, the control unit 50 detects that the document M1 has been placed on the placement surface 12A. Based on the detection that the document M1 has been placed on the placement surface 12A, the control unit 50 performs a document reading process, instructing the reading unit 17 to read the document M1. With this configuration, even if the document cover 15 remains open, the presence of the document M1 on the placement surface 12A of the document tray 12 can be detected with the light-emitting unit 18 turned off, thus enabling document detection with low power consumption. In addition, the operating frequency and operating time of the light-emitting unit 18 can be reduced, thereby reducing the deterioration of the light-emitting unit 18 and extending its lifespan.

[0116] (2) Based on the first reading result, the control unit 50 performs a first determination to determine whether or not the document M1 placed on the mounting surface 12A can be detected. If the result of the first determination indicates that it can be detected, the control unit 50 performs a second reading process. Based on the difference between the second reading result and the first reading result, the control unit 50 performs a second determination to determine whether or not the document M1 has been placed on the mounting surface 12A. If the result of the second determination indicates that it has been placed, the control unit 50 performs the document reading process. With this configuration, the second reading process is performed only when it is confirmed that the document M1 can be detected, so delays in the start of the document reading process due to the execution of unnecessary processes can be suppressed.

[0117] (3) The control unit 50 performs the document reading process with the document cover 15 open. With this configuration, the user can have the document M1 read without closing the document cover 15 after placing the document M1 on the placement surface 12A.

[0118] (4) If the result of the first determination is negative, the control unit 50 performs a third reading process in which the reading unit 17 performs reading with the document cover 15 open and the light-emitting unit 18 lit. With this configuration, if the document M1 placed on the placement surface 12A cannot be detected based on the first reading result, the reading unit 17 performs reading with the document cover 15 open and the light-emitting unit 18 lit, making it easier to detect the document M1.

[0119] (5) The reading unit 17 includes a plurality of image sensors that output brightness signals corresponding to the incident light. In the first determination, the control unit 50 determines that the original document M1 can be detected if there is a brightness signal in the brightness signal of the first reading result that exceeds a first threshold. In the second determination, the control unit 50 determines that the original document M1 has been placed on the placement surface 12A if there is difference data in the difference data indicating the difference between the brightness signal of the first reading result and the brightness signal of the second reading result that exceeds a second threshold. With this configuration, it is possible to determine whether or not the original document M1 has been placed with an accuracy corresponding to the resolution of the plurality of image sensors. Therefore, it is possible to reduce judgment errors (original document detection errors) in which the original document M1 is placed but is judged not to be placed, and thus further contribute to reducing power consumption.

[0120] (6) The image reading device 11 includes a carriage 19. The carriage 19 moves the reading unit 17 along the document tray 12. The document tray 12 is provided with a reading window on the outside of the mounting surface 12A in a plan view, which the reading unit 17 can face. The control unit 50 moves the carriage 19 so that the reading unit 17 is facing the reading window and performs the first reading process. With this configuration, even if the document M1 is placed on the document during the first reading process, the first reading process can be performed in a location where the document M1 is not placed.

[0121] (7) The system is further equipped with an open / close sensor that detects the opening and closing of the document cover 15. The control unit 50 performs a first reading process based on the result of the open / close sensor detecting the open state of the document cover 15. With this configuration, the first reading process can be performed after the user has opened the document cover 15 in order to place the document M1 on the placement surface 12A. Therefore, power consumption can be reduced compared to a configuration in which the first reading process is performed before the user opens the document cover 15.

[0122] (8) A document detection method for detecting a document M1 placed on the document table 12 using an image reading device 11 comprising a document table 12, a reading unit 17, a light-emitting unit 18, and a document cover 15 includes the following (A) to (C). (A) With the document cover 15 open and before the document M1 is placed on the placement surface 12A, a first reading process is performed in which the reading unit 17 is made to perform reading with the light-emitting unit 18 turned off. (B) If, based on the results of the first reading process, it is determined that the document M1 placed on the placement surface 12A can be detected, a second reading process is performed in which the reading unit 17 is instructed to perform reading with the document cover 15 open and the light-emitting unit 18 turned off. (C) Based on the difference between the result of the second reading process and the result of the first reading process, the original document M1 placed on the mounting surface 12A is detected.

[0123] This method allows for detection of the placement of the document M1 on the document platen 12's mounting surface 12A even when the document cover 15 is open and the light-emitting unit 18 is turned off, thus enabling document detection with low power consumption.

[0124] (9) A document reading method for reading a document M1 placed on the document table 12 using an image reading device 11 comprising a document table 12, a reading unit 17, a light-emitting unit 18, and a document cover 15 includes the following (A) to (C). (A) With the document cover 15 open and before the document M1 is placed on the placement surface 12A, a first reading process is performed in which the reading unit 17 is made to perform reading with the light-emitting unit 18 turned off. (B) If, based on the results of the first reading process, it is determined that the document M1 placed on the placement surface 12A can be detected, a second reading process is performed in which the reading unit 17 is instructed to perform reading with the document cover 15 open and the light-emitting unit 18 turned off. (C) Based on the difference between the result of the second reading process and the result of the first reading process, it is detected that the original document M1 has been placed on the placement surface 12A. (D) Based on the detection that the document M1 has been placed on the placement surface 12A, the document reading process is executed, causing the reading unit 17 to read the document M1. According to this document scanning method, even if the document cover 15 remains open, the device can detect that the document M1 is placed on the mounting surface 12A of the document glass 12 with the light-emitting unit 18 turned off. Therefore, since document detection can be achieved with low power consumption even when the document cover 15 is open, the document M1 can be scanned with low power consumption.

[0125] <Example of changes> Furthermore, the above embodiment can be modified to a form such as the following modified example. In addition, the above embodiment and the following modified example can be appropriately combined to form a further modified example, and the following modified examples can be appropriately combined to form a further modified example.

[0126] The document cover 15 may be opened or closed by a document placement detection process. The control unit 50 determines that the document cover 15 is open when there is data in the reading data of the reading unit 17 that exceeds the first threshold A1. The control unit 50 determines that the document cover 15 is closed when all of the data in the reading data of the reading unit 17 is at or below the first threshold A1. With this configuration, the reading unit can detect whether the document cover 15 is open or closed. Furthermore, when it is determined that the document cover 15 is open, the degree of opening (opening angle) of the document cover 15 may be detected based on the boundary position BX in the main scanning direction X between data at or below the first threshold A1 (dark data) and data exceeding the first threshold A1 (bright data). In addition, when detecting whether the document cover 15 is open or closed, if the boundary position BX based on the reading data exceeds the threshold BX1 on the main scanning position, it may be determined that the document cover 15 is closed, while if the boundary position BX is at or below the threshold BX1, it may be detected that the document cover 15 is open. In this case, the switching angle at which the document cover 15 is detected when open or closed may be adjusted by changing the setting of the threshold BX1. Thus, the document placement detection process may be used for the cover open / close detection process that detects the opening and closing of the document cover 15. In this case, by using the cover open / close detection process, the open / close sensor 23 may be replaced with the cover open / close detection process, for example, eliminating the open / close sensor 23. Alternatively, the open / close sensor 23 and the cover open / close detection process may be used in combination. In this case, the setting of the switching angle for the open / close of the document cover 15 may be the same or different for the open / close sensor 23 and the cover open / close detection process. Furthermore, the detection result of the open / close sensor 23 may be used to correct the detection result in the cover open / close detection process.

[0127] The determination process in step S11 in Figure 10 may be performed by the cover opening / closing detection process in the above modified example. For example, when the control unit 50 receives a reading execution instruction made by the user operating the operation unit 42, it starts executing the document reading control routine shown in Figure 10, and the determination process for detecting the cover opening in step S11 may be performed by the cover opening / closing detection process.

[0128] The size of the document M1 may be detected using the document placement detection process. When the control unit 50 detects the placement of the document M1 using the document placement detection process, the length of the placed document M1 in the main scanning direction X may be detected based on the read data. The coordinate value of the boundary position X2 (see Figure 7) between the range of main scanning positions taken by data that is less than or equal to the second threshold A2 (black data) and the range of main scanning positions taken by data that exceeds the second threshold A2 (white data) may be detected as the length (depth dimension) of the document M1 in the main scanning direction X. In this case, it is assumed that the document M1 is placed so that its rear edge (-X side) aligns with the first reference edge (X=0) on the rear side (-X side) of the placement surface 12A. Furthermore, the length (width dimension) of the document M1 in the sub-scanning direction Y may also be detected. After detecting the document, with the document cover 15 open and the light-emitting unit 18 turned off, the reading unit 17 is made to scan in the sub-scanning direction Y. Based on the scanned data, the position of the end YM (see Figure 2) of the document M1 in the sub-scanning direction Y is detected. The coordinate value of this detected end YM in the sub-scanning direction Y is taken as the length of the document M1 in the sub-scanning direction Y. In this way, even with the document cover 15 open and the light-emitting unit 18 turned off, the length of the document M1 can be detected using ambient light L. In this case, only the length of the document M1 in the main scanning direction X may be detected, only the length of the document M1 in the sub-scanning direction Y may be detected, or the lengths of the document M1 in both the main scanning direction X and the sub-scanning direction Y may be detected. It is assumed that the document M1 is placed so that the -Y side edge of the document M1 in the sub-scanning direction Y is aligned with the second reference edge (Y0=0) on the -Y side of the placement surface 12A. Alternatively, when scanning in the sub-scanning direction Y of the reading unit 17, the position of the -Y side edge of the document M1 in the sub-scanning direction Y may be similarly detected. For example, after detecting the document, the reading unit 17 is made to scan in the sub-scanning direction Y to detect the positions of the edges YE1 and YE2 on both sides of the document M1 in the sub-scanning direction Y. The control unit 50 may calculate YE2-YE1 to determine the length of the document M1 in the sub-scanning direction Y.

[0129] In the above embodiment, the control unit 50 performed the first reading process with the reading unit 17 at the window position Y1, but the first reading process may also be performed with the reading unit 17 at a position within the document reading area SA. In other words, the first reading position Y1 may be a position within the document reading area SA instead of the window position. In this case, the first reading position Y1, which is the position of the reading unit 17 when performing the first reading process, and the second reading position Y2, which is the position of the reading unit 17 when performing the second reading process, may be the same position or different positions.

[0130] In the above embodiment, the first threshold A1 and the second threshold A2 may be the same value or different values. The opening and closing motion of the document cover 15, which is configured to be rotatable relative to the document table 12, is not limited to a configuration consisting solely of rotational motion. It is sufficient for the document cover 15 to have rotational motion relative to the document table 12 as part of its opening and closing motion, which involves displacement in the main scanning direction X. For example, the opening and closing motion of the document cover 15 may include an upward motion in which the document cover 15 rises while maintaining a predetermined posture, or a horizontal motion in which it slides horizontally in the X direction.

[0131] The control unit 50 may perform the document scanning process with the document cover 15 closed. The control unit 50 may be configured not to perform the first determination. For example, the determination process in step S15 in Figure 10 may be omitted.

[0132] When the open / close sensor 23 detects that the document cover 15 is open, the photoelectric conversion time of the line sensor 17L constituting the reading unit 17 during image reading may be the same as the photoelectric conversion time during normal image reading, or it may be longer as described in Patent Document 1.

[0133] Before scanning the original document M1, a preliminary scanning operation (pre-scan) may be performed to detect the size of the original document M1. In this case, after performing the document placement detection process in the above embodiment and the above modified example, and detecting that the original document M1 has been placed, the preliminary scanning operation (pre-scan) may be performed. The preliminary scanning operation may also be an image confirmation operation for the user to check the original document image in advance, instead of a size detection operation. The original document image scanned in the preliminary scanning operation may be previewed on the display unit of an external device such as a PC.

[0134] After detecting the placement of a document using the document placement detection process described in the above embodiment and the above modified example, the size of the document may be detected using the method described in Patent Document 1. The reading unit 17 may be a CCD (Charge-Coupled Device) type (reduction optical type), not limited to the CIS type.

[0135] • The original document M1 is not limited to this B1 or booklet; it may also be printed paper. In this case, the paper may be larger or smaller than the mounting surface 12A. The original document M1 may be placed so that a portion extends beyond the mounting surface 12A, or it may be placed without extending beyond the surface. The original document M1 may also be a three-dimensional object other than this B1. In addition, it may be any other type of original document for which scanning is preferable with the original document cover 15 open.

[0136] Each functional unit within the control unit 50 is not limited to being implemented by the CPU; for example, it may be implemented in hardware using electronic circuits such as ASICs (application-specific integrated circuits) and FPGAs (field-programmable gate arrays), or it may be implemented using both software and hardware. For example, some or all of the parts 61 to 67 that constitute the control unit 50 shown in Figure 5 may be implemented in hardware instead of software. For example, the control unit 50 may include an ASIC, and at least some or all of the parts 61 to 67 may be implemented by an ASIC or FPGA.

[0137] The image reading device 11 may not be configured to include an automatic paper feeder 24. In other words, the image reading device 11 may be a flatbed image reading device that does not have an ADF (Automatic Document Feeder) type image reading function.

[0138] The image reader 11 may be mounted on top of the printer as part of the multifunction device. In other words, the image reader 11 may be part of a multifunction device mounted on top of the printer. This type of multifunction device may be a consumer multifunction device for personal or home use, or a business or office multifunction device.

[0139] As used herein, the expression "at least one" means "one or more" of the desired options. For example, as used herein, if there are two options, the expression "at least one" means "only one option" or "both of the two options." As another example, as used herein, if there are three or more options, the expression "at least one" means "only one option" or "any combination of two or more options."

[0140] <Technical philosophy> The technical concepts and their effects, as understood from the above embodiments and modified examples, are described below. [1] The image reading device comprises a document tray having a surface on which a document is placed, a reading unit that reads a document placed on the front surface of the document tray from the opposite side of the front surface, a light-emitting unit that can be switched on and off and illuminates the document from the opposite side of the front surface of the document tray when lit, a document cover that opens and closes the front surface of the document tray, and a control unit. The control unit executes a document reading process that causes the reading unit to read a document based on the difference between a first reading result obtained by a first reading process in which the reading unit performs reading with the light-emitting unit turned off when the document cover is open and a document is not placed on the front surface, and a second reading result obtained by a second reading process in which the reading unit performs reading with the document cover open and the light-emitting unit turned off, and the control unit detects that a document has been placed on the front surface. With this configuration, even if the document cover is open, the system can detect that a document has been placed on the document tray surface with the light-emitting unit turned off, thus enabling document detection with low power consumption.

[0141] [2] In the image reading device described in [1] above, the control unit may perform a first determination based on the first reading result to determine whether or not the document placed on the aforementioned surface can be detected, and if the result of the first determination indicates that it can be detected, it may perform the second reading process, and if the result of the second determination indicates that it can be detected, it may perform the document reading process. With this configuration, the second reading process is performed only when it is confirmed that the document can be detected, so delays in starting the document reading process due to the execution of unnecessary processes can be suppressed.

[0142] [3] In the image reading device described in [2] above, the control unit may perform the document reading process with the document cover open. With this configuration, the user can have the document read without closing the document cover after placing the document on the placement surface.

[0143] [4] In the image reading device described in [2] or [3] above, the control unit may perform a third reading process in which, if the result of the first determination is negative, the reading unit performs reading with the document cover open and the light-emitting unit lit. With this configuration, if the document placed on the placement surface cannot be detected based on the first reading result, the reading unit performs reading with the document cover open and the light-emitting unit lit, making it easier to detect the document.

[0144] [5] In the image reading device described in any one of [2] to [4] above, the reading unit includes a plurality of image sensors that output a luminance signal corresponding to the incident light, and the control unit may, in the first determination, determine that a document can be detected if there is a luminance signal in the first reading result that exceeds a first threshold, and in the second determination, determine that a document has been placed on the aforementioned surface if there is difference data in the difference data indicating the difference between the luminance signal in the first reading result and the luminance signal in the second reading result that exceeds a second threshold. With this configuration, it is possible to determine whether or not a document has been placed with an accuracy corresponding to the resolution of the plurality of image sensors. Therefore, it is possible to reduce judgment errors (document detection errors) in which a document is placed but is judged not to be placed, and thus further contribute to reducing power consumption.

[0145] [6] An image reading device according to any one of [1] to [5] above, further comprising a carriage for moving the reading unit along the document glass, wherein the document glass is provided with a reading window portion on the outside of the aforementioned surface in a plan view, on which the reading unit can face, and the control unit may perform the first reading process with the reading unit facing the reading window portion by moving the carriage. With this configuration, even if a document is placed on the document during the first reading process, the first reading process can be performed in a location where no document is placed.

[0146] [7] The image reading device described in any one of [1] to [6] above is further provided with an open / close sensor for detecting the opening and closing of the document cover, and the control unit may perform the first reading process based on the result of the open / close sensor detecting the open state of the document cover. With this configuration, the first reading process can be performed after the user has opened the document cover. Therefore, power consumption can be reduced compared to a configuration in which the first reading process is performed before the user opens the document cover.

[0147] [8] The document detection method is an image reading device that detects a document placed on the document table, comprising: a document table having a surface on which a document is placed; a reading unit that reads a document placed on the aforementioned surface of the document table from the opposite side of the aforementioned surface; a light-emitting unit that can be switched on and off, and when lit, illuminates the document through the document table from the opposite side of the aforementioned surface of the document table; and a document cover that opens and closes the aforementioned surface of the document table, wherein the device detects a document placed on the document table using an image reading device, wherein, when the document cover is in the open state and before a document is placed on the aforementioned surface, the device performs a first reading process in which the reading unit performs reading with the light-emitting unit turned off, and if it is determined that a document placed on the aforementioned surface can be detected based on the result of this first reading process, the device performs a second reading process in which the reading unit performs reading with the document cover in the open state and the light-emitting unit turned off, and the document placed on the aforementioned surface is detected based on the difference between the result of the second reading process and the result of the first reading process. This document detection method allows for the detection of a document being placed on the document tray surface even when the document cover is open, with the light-emitting unit turned off, thus enabling document detection with low power consumption.

[0148] [9] A document reading method is an image reading device comprising: a document table having a surface on which a document is placed; a reading unit that reads a document placed on the front surface of the document table from the opposite side of the front surface; a light-emitting unit that can be switched on and off, and when lit, illuminates the document through the document table from the opposite side of the front surface of the document table; and a document cover that opens and closes the front surface of the document table, wherein the document reading method reads a document placed on the document table, and the light-emitting unit is turned off before the document cover is open and the document is placed on the front surface. Based on the result of the first reading process, in which the reading unit performs reading with the document cover in place, if it is determined that the document placed on the aforementioned surface can be detected, a second reading process is performed in which the reading unit performs reading with the document cover open and the light-emitting unit turned off. Based on the difference between the result of the second reading process and the result of the first reading process, it is detected that a document has been placed on the aforementioned surface, and based on the detection that a document has been placed on the aforementioned surface, a document reading process is performed in which the reading unit reads the document. With this document reading method, even if the document cover remains open, it is possible to detect that a document has been placed on the surface of the document tray with the light-emitting unit turned off. Therefore, since document detection can be achieved with low power consumption even if the document cover remains open, document reading can be performed with low power consumption. [Explanation of symbols]

[0149] 11…Image reading device, 12…Document tray, 12A…Placement surface, 13…Housing, 14…Transparent plate, 15…Document cover, 15A…Bottom surface, 15B…Rotating end, 17…Reading unit (first reading unit), 17L…Line sensor, 18…Light-emitting unit, 19…Carriage, 20…Reading module, 21…Reading window, 22…Transparent plate, 23…Open / close sensor, 24…Automatic paper feeder, 25…Transport path, 26…Supply tray, 27...Support unit, 28...Image sensor, 29...Light guide member, 30...Transport unit, 31...Pick roller, 32...Transport roller, 33...Discharge tray, 34...Detection unit, 35...Double feed detection unit, 37...Reading unit (second reading unit), 38...Light emitting unit, 39...Support unit, 40...Reading module, 41...Display unit, 42...Operation unit, 43...Carriage motor, 44...Scanning mechanism, 45...Guide member, 46...Power Transmission mechanism, 50... Control unit, 51... Image reading control unit, 52... Memory, 61... Carriage drive control unit, 62... Reading control unit, 63... Light emission control unit, 64... Cover opening / closing determination unit, 65... Display control unit, 66... ​​First determination unit, 67... Second determination unit, 70... Illumination unit, PR... Control program, D1... Threshold data, A1... First threshold, A2... Second threshold, SA... Document reading area, L... Ambient light, LA... Bright area Area, CS...Dark area, MS...Dark area, SD0...First reading result, SD1...First reading result, SD2...Second reading result, X1...First position, X2...Second position, M1...Original document, ME...Edge, B1...Book, Y1...First reading position (window position), Y2...Second reading position, Y0...Base end, YE...End, YM...Edge, ΔL...Difference data, X...Main scanning direction (depth direction), Y...Sub-scanning direction (width direction), Z...Vertical direction.

Claims

1. A document tray having a surface on which the document is placed, A reading unit that reads a document placed on the front surface of the document holder from the opposite side of the front surface, The light-emitting unit can be switched on and off, and when lit, it illuminates the document from the opposite side of the front surface of the document tray. A document cover that opens and closes the aforementioned surface of the document holder, It comprises a control unit and, Image reading device, wherein the control unit detects that a document has been placed on the aforementioned surface, based on the difference between a first reading result obtained by a first reading process in which the reading unit performs reading with the light-emitting unit turned off while the document cover is open and before the document is placed on the aforementioned surface, and a second reading result obtained by a second reading process in which the reading unit performs reading with the document cover open and the light-emitting unit turned off, the control unit then performs a document reading process in which the reading unit reads the document, based on the detection that a document has been placed on the aforementioned surface.

2. The image reading device according to claim 1, wherein the control unit performs a first determination to determine whether or not a document placed on the aforementioned surface can be detected based on the first reading result, and if the result of the first determination indicates that it can be detected, it performs the second reading process, and if the result of the second determination indicates that a document has been placed on the aforementioned surface, it performs the document reading process.

3. The image reading device according to claim 2, wherein the control unit performs the document reading process with the document cover open.

4. The image reading device according to claim 2, wherein the control unit, when the result of the first determination is negative, performs a third reading process in which the reading unit performs reading with the document cover open and the light-emitting unit illuminated.

5. The reading unit includes a plurality of image sensors that output brightness signals corresponding to the incident light. The image reading device according to claim 2, wherein the control unit determines in the first determination that a document can be detected if there is a luminance signal in the first reading result that exceeds a first threshold, and in the second determination that a document has been placed on the aforementioned surface if there is difference data in the difference data indicating the difference between the luminance signal in the first reading result and the luminance signal in the second reading result that exceeds a second threshold.

6. The reading unit further comprises a carriage for moving along the document tray, The document tray is provided with a reading window on the outside of the aforementioned surface, in a plan view, that can face the reading unit. The image reading device according to claim 2, wherein the control unit performs the first reading process with the reading unit facing the reading window by moving the carriage.

7. The system further includes an open / close sensor for detecting the opening and closing of the document cover, The image reading device according to claim 2, wherein the control unit performs the first reading process based on the result of the opening / closing sensor detecting the open state of the document cover.

8. A document tray having a surface on which the document is placed, A reading unit that reads a document placed on the front surface of the document holder from the opposite side of the front surface, The light-emitting unit can be switched on and off, and when lit, it illuminates the document through the document tray from the opposite side of the front surface of the document tray. A document detection method for detecting a document placed on the document table using an image reading device comprising a document cover that opens and closes the document surface of the document table, A document detection method comprising: performing a first reading process in which the reading unit performs reading with the light-emitting unit turned off while the document cover is open and before the document is placed on the aforementioned surface, and determining that the document placed on the aforementioned surface can be detected based on the result of the first reading process, performing a second reading process in which the reading unit performs reading with the document cover open and the light-emitting unit turned off, and detecting the document placed on the aforementioned surface based on the difference between the result of the second reading process and the result of the first reading process.

9. A document tray having a surface on which the document is placed, A reading unit that reads a document placed on the front surface of the document holder from the opposite side of the front surface, The light-emitting unit can be switched on and off, and when lit, it illuminates the document through the document tray from the opposite side of the front surface of the document tray. A document reading method for reading a document placed on the document table using an image reading device comprising a document cover that opens and closes the document surface of the document table, A document reading method comprising: first reading process performed with the document cover in the open state and before a document is placed on the aforementioned surface, with the light-emitting unit turned off, causing the reading unit to perform reading; second reading process performed with the document cover in the open state and the light-emitting unit turned off, causing the reading unit to perform reading; detection of a document being placed on the aforementioned surface based on the difference between the result of the second reading process and the result of the first reading process; and document reading process performed with the reading unit reading the document based on the detection that a document has been placed on the aforementioned surface.

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