Image reading apparatus, image forming apparatus, and image reading method

Abstract

The purpose is to read images without any missing parts when reading documents or other objects being transported. [Solution] The system includes: a maximum size setting unit that sets a maximum size including the maximum width and maximum length of multiple objects to be transported; a reading area setting unit that sets a reading area length which is the reading length required to read the objects to be transported, and a first length which is the reading length required to read the object downstream from the leading edge in the transport direction, according to the maximum size set by the maximum size setting unit; an object detection unit that detects the leading edge of the object to be transported; and an image reading unit that starts reading from a position downstream of the leading edge detected by the object detection unit by the first length in the transport direction, and stops reading the image when the read length becomes the length of the reading area.

Description

Technical Field

[0006] , , ,

[0001] The present invention relates to an image reading apparatus, an image forming apparatus, and an image reading method.

Background Art

[0002] Conventionally, an electro-skew correction technique has been used to correct skew and registration deviation during reading by image processing based on the skew (tilt) and registration of a document detected from a read image obtained by reading a document with an automatic document feeder (ADF). Further, it is known that, in order to perform electro-skew correction, the peripheral portion of the document is read additionally.

[0003] Patent Document 1 discloses a configuration using a reading start instruction means for instructing reading start from a position a predetermined distance before the leading edge of a document detected by a paper detection sensor passes through an image reading position, and a reading end instruction means for instructing reading end after additionally reading a predetermined distance after the trailing edge of the document detected by the paper detection sensor passes through the image reading position.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, according to the conventional technique, since the case where a plurality of documents having different widths are mixed is not considered, there is a problem that when a large-angle skew occurs in such a case, a defect occurs in the document of the read image.

[0005] The present invention has been made in view of the above, and an object thereof is to read an image without a defect in reading a conveyance object such as a document.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, the present invention includes: a maximum size setting unit that sets a maximum size including the maximum width and maximum length of a plurality of transport objects; a reading area setting unit that sets a reading area length which is the reading length required to read the transport object, and a first length which is the reading length required to read the transport object downstream from the tip of the transport object, according to the maximum size set by the maximum size setting unit; an object detection unit that detects the tip of the transport object being transported; and an image reading unit that starts reading from a position downstream of the tip detected by the object detection unit by the first length in the transport direction, and ends reading the image when the length read becomes the length of the reading area. [Effects of the Invention]

[0007] According to the present invention, the effect is that images without defects can be read when reading transported objects such as documents. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic cross-sectional view showing the general configuration of an image forming apparatus according to the first embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing the general configuration of the scanner. [Figure 3] Figure 3 is a schematic cross-sectional view showing the general configuration of the ADF. [Figure 4] Figure 4 is a schematic diagram showing the configuration near the document reading position. [Figure 5] Figure 5 shows a schematic configuration of the main scanning sensor and sub-scanning sensor viewed from directly above. [Figure 6] Figure 6 is a block diagram showing the hardware configuration of an image forming apparatus. [Figure 7] Figure 7 shows an example of multiple documents placed in a document tray. [Figure 8] Figure 8 shows an example of a document being transported and the scanning area. [Figure 9] Figure 9 is a block diagram showing the functions of the image processing unit according to the first embodiment. [Figure 10] Figure 10 shows an example of the maximum size that can be set by the maximum size setting unit. [Figure 11] Figure 11 illustrates the relationship between the document being transported and the scanning area. [Figure 12] Figure 12 shows an example of information corresponding to each document size of a standard-sized document. [Figure 13] Figure 13 illustrates the length of the document that needs to be read downstream from the leading edge. [Figure 14] Figure 14 is a flowchart showing an example of the reading process procedure according to the first embodiment. [Figure 15] Figure 15 is a block diagram showing the functions of the image processing unit according to the second embodiment. [Figure 16] Figure 16 illustrates the relationship between the document being transported and the reading area set in the second mode. [Figure 17] Figure 17 is a flowchart showing an example of the reading process procedure according to the second embodiment. [Figure 18] Figure 18 is a block diagram showing the functions of the image processing unit according to the third embodiment. [Figure 19] Figure 19 shows an example of a scanned image and the scanned original document. [Figure 20] Figure 20 shows examples of read images and corrected images. [Figure 21] Figure 21 shows an example of the document size detected by the size detection unit. [Figure 22] Figure 22 shows examples of corrected and output images. [Figure 23] Figure 23 is a flowchart showing an example of the procedure for generating an output image according to the third embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the image reading apparatus, image forming apparatus, and image reading method will be described in detail below with reference to the attached drawings.

[0010] (First Embodiment) FIG. 1 is a cross-sectional view schematically showing a schematic configuration of an image forming apparatus 100 according to the first embodiment. The image forming apparatus 100 is, for example, a multifunction device having at least two functions among a copying function, a printer function, a scanner function, and a facsimile function.

[0011] As shown in FIG. 1, the image forming apparatus 100 includes a paper feeding unit 103, an apparatus main body 104, a scanner 101, and an automatic document feeder (ADF) 102.

[0012] The image forming apparatus 100 includes a plotter 120, which is an image forming unit, inside the apparatus main body 104. The plotter 120 includes a tandem type image forming unit 105, a registration roller 108 that supplies recording paper from the paper feeding unit 103 to the image forming unit 105 via a conveyance path 107, an optical writing device 109, a fixing unit 110, and a duplex tray 111.

[0013] Four photosensitive drums 112 are arranged in parallel in the image forming unit 105 corresponding to four colors of Y (yellow), M (magenta), C (cyan), and K (key plate (black)). Image forming elements including a charger, a developing device 106, a transferrer, a cleaner, and a discharger are arranged around each photosensitive drum 112.

[0014] In addition, an intermediate transfer belt 113 stretched between a driving roller and a driven roller while being sandwiched between the nip of the transferrer and the photosensitive drum 112 is arranged.

[0015] In this tandem-type image forming apparatus 100, based on the scanned image obtained by scanning the original document sent from the ADF 102 with the scanner 101, the optical writing device 109 performs optical writing to each color of the YMCK toner on the corresponding photoreceptor drum 112, the developer unit 106 develops each toner color, and the images are primary transferred onto the intermediate transfer belt 113 in the order of, for example, Y, M, C, K. Then, the image forming apparatus 100 performs a secondary transfer of the full-color image superimposed by the four colors through the primary transfer onto the recording paper supplied from the paper feeding unit 103, fixes it in the fuser unit 110, and ejects the paper to form a full-color image on the recording paper.

[0016] Next, we will describe scanner 101.

[0017] Figure 2 is a schematic cross-sectional view showing the general configuration of the scanner 101. As shown in Figure 2, the scanner 101 comprises a first carriage 25, a second carriage 26, an imaging lens 27, and an imaging unit 28, and each of these components is arranged inside the main frame 101a of the scanner 101.

[0018] Furthermore, a first rail and a second rail (not shown) are provided inside the main frame 101a of the scanner 101, extending in the sub-scanning direction (left-right direction in Figure 2). The first rail consists of two rails arranged at a predetermined distance apart in the main scanning direction perpendicular to the sub-scanning direction. The second rail has the same configuration as the first rail.

[0019] The first carriage 25 is slidably mounted on the first rail and is configured to reciprocate between the position shown by the solid line and the position shown by the dashed line in Figure 2 via a drive wire for the first carriage (not shown) driven by a drive motor (not shown). The first carriage 25 is provided with a light source 24 and a first mirror member 25a.

[0020] Furthermore, the second carriage 26 is slidably mounted on the second rail and is configured to reciprocate between the position shown by the solid line and the position shown by the dashed line in Figure 2 via a drive wire for the second carriage (not shown) driven by a drive motor (not shown). The second carriage 26 is provided with a second mirror member 26a and a third mirror member 26b.

[0021] Here, the first carriage 25 and the second carriage 26 move in the sub-scanning direction at a speed ratio of 2:1. Due to this relationship of movement speeds, even when the first carriage 25 and the second carriage 26 move, the optical path length of the light from the document surface to the imaging lens 27 does not change.

[0022] The imaging lens 27 focuses and images the reflected light from the original document, which is incident on each mirror member, onto the imaging unit 28. The imaging unit 28 is composed of an image sensor such as a CCD (Charge Coupled Device), and it converts the reflected light image of the original document formed via the imaging lens 27 into an analog image signal, which is the scanned image.

[0023] Next, we will describe the ADF 102 mounted on the scanner 101.

[0024] Figure 3 is a schematic cross-sectional view showing the general configuration of the ADF 102. As shown in Figure 3, the ADF 102 includes a document tray 11 on which documents are placed. The document tray 11 has a movable document table 41 that rotates in directions a and b in the figure with its base end as a pivot point, and a pair of side guide plates 42 that position the document in the left-right direction relative to the paper feeding direction (transport direction). By rotating the movable document table 41, the front end of the document in the feeding direction is adjusted to an appropriate height. Note that the document is an example of an object to be transported.

[0025] Furthermore, the document tray 11 is equipped with a main scanning sensor 89 and a sub-scanning sensor 90. As will be described later, the main scanning sensor 89 detects the document width, which is the dimension of the document in the direction perpendicular to the transport direction (main scanning direction), and the sub-scanning sensor 90 detects the document length, which is the dimension of the document in the transport direction (sub-scanning direction).

[0026] The main scanning sensor 89 is a sensor array consisting of multiple sensors spaced apart in the main scanning direction, and the sub-scanning sensor 90 is a sensor array consisting of multiple sensors spaced apart in the sub-scanning direction. The main scanning sensor 89 and the sub-scanning sensor 90 can be reflective sensors that detect without contact by optical means, or contact-type actuator sensors. Note that the main scanning sensor 89 is an example of a first sensor, and the sub-scanning sensor 90 is an example of a second sensor.

[0027] The pair of side guide plates 42 are slidable in the main scanning direction and are configured to accommodate documents of different sizes.

[0028] A set filler 46, which rotates when a document is placed on it, is provided on the fixed side of a pair of side guide plates 42. A document set sensor 82, which detects when a document is placed on the document tray 11, is provided at the lowest point of the movement trajectory of the tip of the set filler 46. In other words, the document set sensor 82 detects whether or not a document is set in the ADF 102 by determining whether or not the set filler 46 rotates and moves away from the document set sensor 82.

[0029] The ADF102 includes a transport unit 50 which is composed of a separation and feeding unit 51, a pull-out unit 52, a turn unit 53, a first reading and transport unit 54, a second reading and transport unit 55, and a paper discharge unit 56. Each transport roller of the transport unit 50 is rotationally driven by one or more transport motors.

[0030] The separation and feeding unit 51 includes a pickup roller 61 positioned near the paper feed opening 60 for feeding documents, and a paper feed belt 62 and a reverse roller 63 positioned opposite each other across the transport path.

[0031] The pickup roller 61 is supported by a support arm member 64 attached to the paper feed belt 62, and moves up and down in directions c and d in the figure between a contact position where it contacts the stack of documents and a separation position away from the stack of documents via a cam mechanism (not shown). At the contact position, the pickup roller 61 picks up several documents (ideally one) from the documents stacked on the document tray 11.

[0032] The paper feed belt 62 rotates in the feeding direction, and the reverse roller 63 rotates in the opposite direction to the feeding direction. In addition, if a document is double-fed, the reverse roller 63 rotates in the opposite direction to the paper feed belt 62. However, when the reverse roller 63 is in contact with the paper feed belt 62, or when only one document is being transported, it rotates together with the paper feed belt 62 due to the action of a torque limiter (not shown). This prevents double-feeding of documents.

[0033] The pull-out section 52 has a pull-out roller 65 consisting of a pair of rollers arranged to straddle the transport path 52a. The pull-out section 52 performs primary skew correction (so-called skew correction) on the fed-out document based on the driving timing of the pull-out roller 65 and the pickup roller 61, and then pulls out and transports the aligned document.

[0034] The turning section 53 has an intermediate roller 66 and a reading entrance roller 67, which consist of a pair of rollers arranged to sandwich a transport path 53a that curves from top to bottom. The turning section 53 turns the original document, which has been pulled out and transported by the intermediate roller 66, by transporting it along the curved transport path, and then transports it with the reading entrance roller 67 with the surface of the original document facing downwards to the vicinity of the slit glass 7, which is the reading position (imaging position) of the original document.

[0035] Here, the transport speed of the document from the pull-out section 52 to the turn section 53 is set to be faster than the transport speed in the first reading transport section 54. This reduces the transport time of the document to be transported to the first reading transport section 54.

[0036] The first reading and transport unit 54 includes a first reading roller 68 positioned opposite the slit glass 7 and a first reading exit roller 69 positioned on the transport path 55a after reading is complete. The first reading and transport unit 54 transports the document as it is transported to the vicinity of the slit glass 7, while the surface of the document is brought into contact with the slit glass 7 by the first reading roller 68. At this time, the document is read by the scanner 101 through the slit glass 7 at the reading position. At this time, the first carriage 25 and the second carriage 26 of the scanner 101 are stopped at the home position. The first reading and transport unit 54 further transports the document after reading is complete using the first reading exit roller 69.

[0037] Figure 4 schematically shows the configuration near the document reading position. In Figure 4, the document is transported from left to right.

[0038] As shown in Figure 4, the ADF 102 is equipped with a background member 92, which serves as the imaging background, at a position opposite the slit glass 7. The background member 92 is, for example, white and is used for shading correction. The original document is transported between the slit glass 7 and the background member 92. The scanner 101 performs image reading at the reading position shown in Figure 4.

[0039] The second reading and transport unit 55 in Figure 3 includes a second reading unit 91 for reading the back side of the document, a second reading roller 70 positioned opposite the second reading unit 91 across the transport path 55a, and a second reading exit roller 71 positioned downstream of the second reading unit 91 in the transport direction.

[0040] In the second reading and transport unit 55, the back side of the document after the front side has been read is read by the second reading unit 91. The document with the back side read is transported toward the paper output tray by the second reading exit roller 71. The second reading roller 70 suppresses the lifting of the document in the second reading unit 91 and also serves as a reference white area for acquiring shading data in the second reading unit 91. If double-sided reading is not performed, the document passes through the second reading unit 91 without any problems.

[0041] The paper output section 56 is equipped with a pair of paper output rollers 72 near the paper output opening, and the documents conveyed by the second reading outlet roller 71 are output to the paper output tray 12.

[0042] Furthermore, the ADF102 is equipped with various sensors along the transport path, such as a stop sensor 84, a resist sensor 81, and a paper ejection sensor 83, which are used for transport control, including the transport distance and transport speed of the document.

[0043] Furthermore, a document width sensor 85 is provided between the pull-out roller 65 and the intermediate roller 66. The length of the document in the transport direction is detected from the motor pulse by reading the leading and trailing ends of the document with a stop sensor 84 and a resist sensor 81. The resist sensor 81 is an example of an object detection unit that detects the document being transported (object to be transported). The leading end of the document is the end of the document on the downstream side in the transport direction, and the trailing end of the document is the end of the document on the upstream side in the transport direction.

[0044] Figure 5 is a top-down view of the schematic configuration of the main scanning sensor 89 and the sub-scanning sensor 90. As shown in Figure 5, the sensor array constituting the main scanning sensor 89 is provided on the movable document table 41, and the sensor array constituting the sub-scanning sensor 90 is provided on the document tray 11.

[0045] When a document is placed on the document tray 11, a portion of the sub-scanning sensor 90, which is positioned in the sub-scanning direction, is covered by the document, and the length of the document can be detected according to which sensor position is triggered.

[0046] Similarly, when the side guide plate 42 is closed to match the placed document, the side guide plate 42 obstructs a portion of the main scanning sensor 89, which is positioned in the main scanning direction, allowing the document width to be detected according to which sensor position has reacted.

[0047] In the following, the main scanning sensor 89 and the sub-scanning sensor 90 may be collectively referred to as the document size detection sensor. Each sensor constituting the document size detection sensor is installed, for example, near the midpoint between two adjacent sizes so that multiple documents of standard sizes can be distinguished.

[0048] When detecting the document width based on the center position in the main scanning direction, the right edge of the document (the boundary on the right side in the main scanning direction) is located 105 mm from the center position for an A4 portrait document (width 210 mm). Here, the orientation of the document (whether the document is placed vertically or horizontally) is defined as vertical when the long side is parallel to the sub-scanning direction, and horizontal when the short side is parallel to the sub-scanning direction.

[0049] Similarly, the right edge of the document is located 91 mm from the center for a B5 portrait document (182 mm wide) and 74 mm from the center for an A5 portrait document (148 mm wide). In this case, the sensor will be positioned midway between the right edges of each document size (approximately 98 mm and 82.5 mm from the center). The above explains size detection in the main scanning direction, but the same applies to size detection in the sub-scanning direction.

[0050] As described above, when sensors are installed discretely, accurate size detection is not possible for documents of irregular size. However, it is possible to determine whether the side guide plate 42 is inside the sensor position from the response of each sensor and obtain an approximate size. For example, using the sensors described above for the main scanning sensor 89, the width of irregularly shaped documents can be detected as "170mm (82.5×2) or less," "more than 170mm to 192mm (96×2) or less," and "more than 192mm." Alternatively, increasing the number of sensors can improve the resolution of the detectable size and enable more accurate size detection.

[0051] Next, the hardware configuration of the image forming apparatus 100 will be described.

[0052] Figure 6 is a block diagram showing the hardware configuration of the image forming apparatus 100. As shown in Figure 6, the image forming apparatus 100 is equipped with an image processing unit 200 that performs predetermined processing on the scanned image obtained by the scanner 101 from the original document transported by the ADF 102, and outputs it as image data to the plotter 120. The scanner 101, ADF 102, and image processing unit 200 constitute an image reading apparatus.

[0053] The image processing unit 200 includes a CPU (Central Processing Unit) 201, ROM (Read Only Memory) 202, main memory 205, chipset 206, image processing ASIC 207, controller ASIC 208, main memory 209, and I / O ASIC 210. ASIC stands for Application Specific Integrated Circuit.

[0054] The CPU 201 controls the image forming apparatus 100. The main memory 205 is used as a work area where the program for the CPU 201 to control the image forming apparatus 100 is deployed, and also as image memory for temporarily storing image data and other data handled. The chipset 206 is used together with the CPU 201 and controls the controller ASIC 208 and I / O ASIC 210 to access the main memory 205.

[0055] The program executed by the image forming apparatus 100 of this embodiment may be configured to be provided as a file in an installable or executable format, recorded on a computer-readable recording medium such as a CD-ROM, flexible disk (FD), CD-R, or DVD (Digital Versatile Disk).

[0056] Furthermore, the program executed by the image forming apparatus 100 of this embodiment may be stored on a computer connected to a network such as the Internet and provided by downloading it via the network. Alternatively, the program executed by the image forming apparatus 100 of this embodiment may be provided or distributed via a network such as the Internet.

[0057] The ADF102 has the function of transporting the original document to the scanner 101. The scanner 101 has the function of reading image data from the original document for copying or for outputting to an external interface. The plotter 120 has the function of printing the image data processed by the controller ASIC208.

[0058] The image processing ASIC 207 performs image processing on the image data read by the scanner 101 and outputs the image data to the controller ASIC 208. The image processing ASIC 207 also processes the image data from the controller ASIC 208 so that it can be printed by the plotter 120, and sends the image data in accordance with the printing timing of the plotter 120.

[0059] The controller ASIC 208 uses the main memory 205 via the chipset 206 to rotate and edit image data handled by the image forming apparatus 100, stores it in the HDD (Hard Disk Drive) 211, and sends and receives image data with the image processing ASIC 207. The main memory 209 is used as image memory for image processing by the controller ASIC 208. The HDD 211 is used for temporary storage of the processed image data.

[0060] The I / O ASIC210 is an external interface for providing additional functions to the image forming apparatus 100. For example, the I / O ASIC210 includes interfaces such as a network interface, USB (Universal Serial Bus), SD (Secure Digital) card, control unit, SPI (Serial Peripheral Interface), I2C (Inter Integrated Circuit), and a document width sensor 85, as well as a hardware accelerator for speeding up image processing and an encryption processing circuit.

[0061] Here, we will use Figures 7 and 8 to explain the loss of original documents that occurs in scanned images using conventional techniques.

[0062] Figure 7 shows an example of multiple documents placed in the document tray 11. Hereafter, multiple documents will be referred to as "multiple documents." Figure 7(a) shows an example of two documents of the same width being placed, and Figure 7(b) shows an example of two documents of different widths being placed. Due to recent revisions to the Electronic Bookkeeping Act and the spread of DX (Digital Transformation), the opportunities to use irregularly shaped documents have increased, and the opportunities to feed multiple documents of different widths, as shown in Figure 7(b), have also increased.

[0063] In the case of Figure 7(a), the side guide plate 42 can be adjusted to match the width of the original document, so the skew (tilt) of each original document is less likely to become large. On the other hand, in the case of Figure 7(b), the side guide plate 42 cannot be adjusted to match the original document B, so the skew of original document B may become large.

[0064] Figure 8 shows examples of a document being transported and the reading area. Figure 8(a) shows document B and its reading area from Figure 7(a), and Figure 8(b) shows document B and its reading area from Figure 7(b). In Figure 8(a), no skew occurs in document B, and by providing the extended areas shown by diagonal lines outside the leading and trailing ends of document B in the reading area, the document can be read without loss. On the other hand, in Figure 8(b), a large skew occurs in the transported document B, so even if the same extended areas as in Figure 8(a) are provided in the reading area, loss of the document occurs during reading.

[0065] Next, the functions of the image reading device according to this embodiment, which consists of a scanner 101, an ADF 102, and an image processing unit 200, will be described.

[0066] Figure 9 is a block diagram showing the functions of the image processing unit 200 according to the first embodiment. Here, we will describe the characteristic functions of the image processing unit 200 in this embodiment.

[0067] As shown in Figure 9, the image processing unit 200 has a maximum size setting unit 301, a reading area setting unit 302, and an image reading unit 303 as functional units. These functional units may be implemented by an image processing ASIC 207 or a controller ASIC 208, or by the CPU 201 executing a program.

[0068] The maximum size setting unit 301 sets the maximum size of multiple documents placed in the document tray 11 based on the detection results of the document size detection sensor. Here, the maximum size of the documents is the maximum width and maximum length of the multiple documents. For example, if A4 portrait (width 210 mm, length 297 mm) and B5 landscape (width 257 mm, length 182 mm) documents are placed together without tilting, the maximum width is set to 257 mm and the maximum length to 297 mm.

[0069] Figure 10 shows an example of the maximum size set by the maximum size setting unit 301. In Figure 10(a), since the widths of document A and document B are equal, this width is set as the maximum width, and since the length of document A is longer than that of document B, the length of document A is set as the maximum length. In Figure 10(b), although document B is placed at an angle, it is placed within the placement range of document A, so the width and length of document A are set as the maximum width and maximum length, respectively. On the other hand, in Figure 10(c), document B is placed at an angle such that the upstream side in the paper feed direction extends beyond document A. Therefore, the maximum length is set to the length of document B in the paper feed direction, as shown in Figure 10(c).

[0070] The reading area setting unit 302 sets the length of the reading area, which is the reading length required to read the document, and the first length, which is the reading length required to read the document downstream from the leading edge in the transport direction, according to the set maximum size. Figure 11 is a diagram illustrating the relationship between the transported document and the reading area. As shown in Figure 11, the reading area includes an extended area indicated by diagonal lines outside the leading edge of the document (downstream in the transport direction). The length of the reading area is set to be the reading length required to read the document, according to the maximum size. The length of the extended area included in the reading area (the first length) is set to be the reading length required to read the document downstream from the leading edge, according to the maximum size. The width of the reading area is set, for example, to be the width obtained by extending the left and right sides of the maximum width.

[0071] In this embodiment, the number of read lines corresponding to the length of the reading area is referred to as the total number of lines. Here, a read line is a data sequence read in the main scanning direction, and the number of read lines is the number of read lines counted in the sub-scanning direction. The number of read lines corresponding to the first length is referred to as the first number of lines. Therefore, the total number of lines can be said to be the number of read lines required to read the document. Furthermore, the first number of lines can be said to be the number of read lines required to read the document downstream from the leading edge in the transport direction.

[0072] In other words, the reading area setting unit 302 sets the reading area by setting the length of the reading area and the first length, or the total number of lines and the first number of lines, according to the maximum size. The reading area setting unit 302 may also set the length of the reading area and the first length, or the total number of lines and the first number of lines, according to the document transport speed.

[0073] The image reading unit 303 reads the image according to the detection result from the resist sensor 81 and the set reading area. Specifically, the image reading unit 303, triggered by the resist sensor 81 detecting the leading edge of the document being transported, starts reading from a position downstream of the leading edge of the document by a first number of lines (or a first length) in the transport direction, and continues reading the image until the number of lines (or length) read equals the total number of lines (or length of the reading area).

[0074] The resist sensor 81 may be positioned in contact with the reading position. This is to reduce the influence of variations in transport speed on the timing control from when the resist sensor 81 detects the document until reading begins. In such cases, since there is a limit to the first length, the reading area setting unit 302 may set the first number of lines (or first length) to a value that does not depend on the maximum size (for example, a fixed value).

[0075] On the other hand, if there is sufficient distance between the resist sensor 81 and the reading position, the first number of lines (or first length) may be set according to the maximum size, for example, to suppress the increase in the total number of lines (or length of the reading area) when the maximum length is small. This reduces the amount of data in the read image and improves the processing speed. Alternatively, a stop sensor 84 may be used instead of the resist sensor 81 to ensure the distance between the position that detects the leading edge of the document and the reading position.

[0076] In Figure 11, an example is shown in which the target detection unit, the resist sensor 81, is positioned as a single object in the center of the main scanning direction. However, the target detection unit may be composed of multiple sensors arranged in the main scanning direction.

[0077] Next, using Figure 12, we will explain the required scanning length (scanning area length) and number of scanning lines (total number of lines) when scanning multiple standard-sized documents. Figure 12 shows examples of information corresponding to each document size of a standard-sized document.

[0078] Figure 12(a) is a table showing the width and length of each document size. In this example, it is assumed that A4, B5, and A5 documents can be placed in the document tray 11 in either portrait or landscape orientation, and the document size is shown separately for each orientation.

[0079] Figure 12(b) is a table showing the maximum possible skew for each document size in the document tray 11, categorized by maximum width. For example, if the maximum width of multiple documents is A3, the A3 documents included in those documents will not be tilted, resulting in a maximum skew of 0°. However, A5 landscape documents can be tilted up to 45°, resulting in a maximum skew of 45°. The "×" in Figure 12(b) indicates that documents of that size are not included in the multiple documents. For example, if the maximum width of multiple documents is B4, it indicates that A3 and A4 landscape documents are not included in those documents.

[0080] Figure 12(c) is a table showing the length required to scan each document size for each maximum size. For example, if the maximum size of multiple documents is A3, the maximum skew of the A3 documents included in those documents is 0°, so the length required to scan is the length of A3 (420mm). On the other hand, if the maximum skew of the A5 landscape documents included in those documents is 45°, the length required to scan is the length of the A5 landscape document tilted at 45° in the sub-scanning direction (253mm). Note that "×", "width×", and "length×" in Figure 12(c) indicate that a document of that size is not included in the multiple documents. For example, if the maximum size of multiple documents is B4, "length×" indicates that a document with the length of A3 is not included, and "width×" indicates that a document with the width of A4 landscape is not included. Also, if the maximum size of multiple documents is A4 portrait, "×" indicates that a B4 document is not included.

[0081] When scanning multiple standard-sized documents, the scanning area setting unit 302 sets the length of the scanning area according to the maximum size, based on data as shown in Figure 12(c). In the example in Figure 12(c), the scanning area setting unit 302 sets the length of the scanning area to the maximum length (shown in bold) among the "lengths required to scan each document size" corresponding to each maximum size. The scanning area setting unit 302 also sets the number of scanning lines corresponding to the length of the scanning area as the total number of lines.

[0082] The above is an example of scanning multiple standard-sized documents, but generally, based on the maximum size, it is possible to determine the maximum skew of any size document and whether a document of that size can be included in multiple documents corresponding to the maximum size. Furthermore, using the document size and maximum skew, the length of the scanning area and the total number of lines can be calculated. Note that the length of the scanning area and the total number of lines can be calculated each time processing is performed, or pre-calculated values ​​can be stored and retrieved for use.

[0083] Next, the first length and the first number of lines described above will be explained. Figure 13 is a diagram illustrating the length that needs to be read downstream from the leading edge of the document. Here, the document shown in Figure 13 is assumed to be tilted at the maximum skew angle relative to the maximum size. Given the size, orientation, and maximum skew of the document, the "length that needs to be read downstream from the leading edge of the document" shown in Figure 13 can be calculated. Then, by calculating the length required to read the leading edge for each document that may be included in the multiple documents corresponding to the maximum size, and finding the maximum value, the first length corresponding to each maximum size can be determined.

[0084] The reading area setting unit 302 sets the reading length obtained as described above as the first length. The reading area setting unit 302 also sets the number of reading lines corresponding to the first length as the first number of lines. The first length and the first number of lines may be calculated each time processing is performed, or pre-calculated values ​​may be stored and read for use.

[0085] Figure 14 is a flowchart showing an example of the reading process procedure according to the first embodiment. In the following description, the reading process will be explained using the number of lines, but the reading process may also use length instead of the number of lines. First, the maximum size setting unit 301 sets the maximum size of multiple documents (step S100).

[0086] Next, the reading area setting unit 302 sets the reading area (first number of lines and total number of lines) according to the maximum size (step S101). Then, when the resist sensor 81 detects the leading edge of the document being transported (step S102: Yes), the image reading unit 303 starts reading from a position downstream of the first number of lines from the leading edge of the document (step S103).

[0087] On the other hand, if the resist sensor 81 does not detect the leading edge of the document being transported (step S102: No), the process returns to step S102, and the check to see whether or not the leading edge of the document has been detected is repeated.

[0088] If the number of lines read by the image reading unit 303 is equal to the total number of lines set by the reading area setting unit 302 (step S104: Yes), the image reading unit 303 terminates reading (step S105). On the other hand, if the number of lines read by the image reading unit 303 is less than the total number of lines (step S104: No), the process returns to step S104, and the check of the number of lines read is repeated.

[0089] Thus, according to this embodiment, since the image is read using a reading area set according to the maximum size, it is possible to read an image without any missing parts of the original document. Furthermore, by using the read image without any missing parts of the original document for detecting and correcting the skew (tilt) and resist (position) of the original document, it is possible to generate a high-quality image using the highly accurate detection results. In addition, by using the read image without any missing parts of the original document for detecting the size of the original document and for cropping the original document, it is possible to obtain an image of the appropriate size using the highly accurate detection results.

[0090] Although the above description refers to the object to be read as a document, the object to be read by the image reading device according to this embodiment may be something other than a document. The object to be read may be, for example, an object transported on a factory production line (electronic circuit board, wafer, etc.) or an object transported on a conveyor belt in a logistics center (cardboard boxes, containers, etc.).

[0091] (Second Embodiment) Next, a second embodiment will be described.

[0092] The second embodiment allows the document tray 11 to be set to either a first mode in which multiple documents of different widths are placed, or a second mode in which multiple documents of equal width are placed. In the following description of the second embodiment, the description of parts that are the same as those of the first embodiment will be omitted, and the parts that differ from the first embodiment will be described.

[0093] Figure 15 is a block diagram showing the functions of the image processing unit 200 according to the second embodiment. The difference from Figure 9 is that the image processing unit 200 further includes a mode setting unit 321, and the output of the mode setting unit 321 is input to the reading area setting unit 302. Note that each function shown in Figure 15 may be implemented by the image processing ASIC 207 or controller ASIC 208, or by the CPU 201 executing a program.

[0094] The mode setting unit 321 sets either the first mode or the second mode according to information (for example, instructions for setting a mode) entered by the user using the operation unit provided by the I / O ASIC 210. Here, the first mode is set when the width of at least one of the multiple documents placed on the document tray 11 differs from the width of the other documents. The second mode is set when the widths of all the multiple documents placed on the document tray 11 are equal.

[0095] The reading area setting unit 302 sets the reading area according to the mode set by the mode setting unit 321. When the mode setting unit 321 sets the first mode, the reading area setting unit 302 sets the first number of lines and the total number of lines (or the first length and the length of the reading area) in the same manner as in the first embodiment. When the mode setting unit 321 sets the second mode, the reading area setting unit 302 sets the second number of lines and the third number of lines (or the second length and the third length as described later) as shown in Figure 16.

[0096] Figure 16 illustrates the relationship between the document being transported and the reading area set in the second mode. As shown in Figure 16, the reading area includes a leading-edge extension area indicated by diagonal lines outside the leading-edge of the document (downstream in the transport direction) and a trailing-edge extension area indicated by diagonal lines outside the trailing-edge of the document (upstream in the transport direction). In this embodiment, the length of these extension areas is independent of the maximum size. When multiple documents placed on the document tray 11 have the same width, the resulting skew angle is small, so a relatively small value can be set as the length of the extension area. The width of the reading area is set, for example, to be the width obtained by extending the left and right sides of the maximum width.

[0097] In this embodiment, the number of read lines corresponding to the length of the front-end extension area (second length) when the second mode is set is called the second line count. Similarly, the number of read lines corresponding to the length of the rear-end extension area (third length) is called the third line count. That is, the read area setting unit 302 sets the read area by setting the second length and the third length, or the second line count and the third line count. The read area setting unit 302 may also set the second length and the third length, or the second line count and the third line count, according to the document transport speed.

[0098] Figure 17 is a flowchart showing an example of the reading process procedure according to the second embodiment. The difference from Figure 14 is the addition of step S210, which determines whether the set mode is the first mode, and steps S221 to S225, which are steps to take if the set mode is the second mode. The operation of steps S211 to S216 is the same as the operation of steps S100 to S105 in Figure 14, so the explanation is omitted. In the following, the reading process will be described as a process using the number of lines, but the reading process may also be a process using the length instead of the number of lines.

[0099] If the mode setting unit 321 sets the first mode (step S210: Yes), the process proceeds to step S211.

[0100] On the other hand, if the mode setting unit 321 sets a second mode (step S210: No), the process proceeds to step S221. Next, the reading area setting unit 302 sets the reading area by setting the second number of lines and the third number of lines (step S221). Then, if the resist sensor 81 detects the leading edge of the document being transported (step S222: Yes), the image reading unit 303 starts reading from a position two lines downstream from the leading edge of the document (step S223).

[0101] On the other hand, if the resist sensor 81 does not detect the leading edge of the document being transported (step S222: No), the process returns to step S222, and the check to see whether or not the leading edge of the document has been detected is repeated.

[0102] Then, if the resist sensor 81 detects the trailing edge of the document being transported (step S224: Yes), the process proceeds to step S225. On the other hand, if the resist sensor 81 does not detect the trailing edge of the document (step S224: No), the process returns to step S224, and the check to see whether or not the trailing edge of the document has been detected is repeated.

[0103] If the image reading unit 303 has read up to a position three lines upstream from the trailing edge of the original document (step S225: Yes), the image reading unit 303 terminates the reading (step S216). On the other hand, if the number of lines read by the image reading unit 303 upstream from the trailing edge of the original document is less than the third number of lines (step S225: No), the process returns to step S225, and the check of the number of lines read is repeated.

[0104] Thus, according to this embodiment, the scanning area can be set according to whether the set mode is a first mode in which multiple documents have different widths or a second mode in which multiple documents have the same width. Furthermore, in the first mode, images without loss can be scanned from each of the documents with different widths, and in the second mode, memory usage can be reduced and productivity can be improved by scanning with a limited scanning area.

[0105] (Third embodiment) Next, a third embodiment will be described.

[0106] The third embodiment detects skew and resist from the scanned image, corrects for skew and resist, and extracts the document from the scanned image. In the following description of the third embodiment, the parts that are the same as those of the second embodiment will be omitted, and the parts that differ from the second embodiment will be described.

[0107] Figure 18 is a block diagram showing the functions of the image processing unit 200 according to the third embodiment. The difference from Figure 15 is that the image processing unit 200 further includes an outline detection unit 331, a corrected image generation unit 332, a size detection unit 333, and an output image generation unit 334. Note that each of the functional units shown in Figure 18 may be implemented by the image processing ASIC 207 or the controller ASIC 208, or by the CPU 201 executing a program.

[0108] The outline detection unit 331 detects the outline of the original document and outputs a success / failure signal indicating whether the outline detection was successful or not, and an outline signal indicating the outline. Here, the outline of the original document includes the skew and resist of the original document. The outline detection unit 331 detects the boundary using the difference in density and color between the background material 92 included in the scanned image and the original document, and calculates the outline of the original document.

[0109] Figure 19 shows examples of scanned images and scanned originals. Figure 19(a) shows an example where the density and color of the background material 92 and the scanned original are similar. Figure 19(b) shows an example where part of the scanned original is damaged. In scanned images like Figure 19(a), it becomes difficult to detect the boundary between the background material 92 and the original, and the detection of the outline may not be successful (failure). Also, in scanned images like Figure 19(b), it becomes difficult to determine which of the boundaries between the background material 92 and the original should be used to calculate the skew, and the detection of the outline may fail.

[0110] The corrected image generation unit 332 generates a corrected image based on the success / failure signal and outline signal output by the outline detection unit 331, and the image read by the image reading unit 303.

[0111] Figure 20 shows examples of read images and corrected images. Figure 20(a) shows an example of a read image read by the image reading unit 303. Figure 20(b) shows an example of a corrected image when the outline detection unit 331 successfully detects the outline, and Figure 20(c) shows an example of a corrected image when the outline detection unit 331 fails to detect the outline.

[0112] As shown in Figure 20(b), if the outline detection is successful, the correction image generation unit 332 uses the skew and resist information included in the outline signal to orient the original document through rotational correction and generates a correction image that aligns the original document's position to, for example, the center position of the scanned image. In addition, the correction image generation unit 332 may generate a correction image that aligns the original document to any of the top, bottom, left, or right edges of the scanned image during resist correction.

[0113] As shown in Figure 20(c), if the detection of the outline fails, the correction image generation unit 332 does not correct the read image and generates the read image as the correction image as is.

[0114] The size detection unit 333 detects the size of the document. Here, the size of the document includes the width and length of the document.

[0115] Figure 21 shows examples of document sizes detected by the size detection unit 333. Figure 21(a) shows an example of document width when documents A and B, which have the same width, are placed on the document tray 11. Figure 21(b) shows an example of document length detected using the leading and trailing ends of the transported document.

[0116] As shown in Figure 21(a), when multiple documents of the same width are placed on the scanner, the size detection unit 333 detects the maximum width set by the maximum size setting unit 301 as the document width. Also, when multiple documents of the same size are placed on the scanner, the size detection unit 333 detects the maximum width and maximum length set by the maximum size setting unit 301 as the document width and document length.

[0117] As shown in Figure 21(b), when using the leading and trailing ends of the transported document, the size detection unit 333 calculates the document length using, for example, the time difference between when the resist sensor 81 detects the leading end of the document and when it detects the trailing end of the document, and the transport speed. The size detection unit 333 may also use a stop sensor 84 instead of the resist sensor 81 and calculate the document length in the same manner as described above.

[0118] The size detection unit 333 may detect the width of the document using the output of the document width sensor 85. Alternatively, the size detection unit 333 may calculate the document size through image processing. For example, the size detection unit 333 can detect boundaries using the difference in density and color between the background material 92 included in the scanned image and the document, and calculate the document size from the detected boundaries.

[0119] The output image generation unit 334 generates an output image from the corrected image based on the mode set by the mode setting unit 321 and the size of the original document detected by the size detection unit 333.

[0120] Figure 22 shows examples of corrected and output images. Figure 22(a) shows the case where outline detection is successful in the first mode, Figure 22(b) shows the case where outline detection fails in the first mode, Figure 22(c) shows the case where outline detection is successful in the second mode, and Figure 22(d) shows the case where outline detection fails in the second mode.

[0121] If the outline detection is successful in the first mode, the corrected image will be an image with corrected skew and resist, as shown in Figure 22(a). In this case, the output image generation unit 334 generates an output image by cutting out the area indicated by the dashed line from the corrected image based on the original size detected by the size detection unit 333.

[0122] On the other hand, if the outer shape detection fails in the first mode, multiple documents of different widths may be placed on the document tray 11, potentially causing significant skew or large resist misalignment. In such cases, as shown in Figure 22(b), the corrected image will retain significant tilt and misalignment. Furthermore, the reliability of the document size detected by the size detection unit 333 is low, so cropping the output image based on such a document size may result in loss of part of the document. For this reason, the output image generation unit 334 does not crop from the scanned image, but generates the scanned image as the output image. This makes it possible to output an image in which the area of ​​the background member 92 remains, but without any loss of part of the document.

[0123] In the second mode, the output image generation unit 334 performs cropping based on the document size detected by the size detection unit 333, regardless of whether the outline detection is successful or not (i.e., regardless of the success or failure signal). As shown in Figures 22(c) and (d), the output image generation unit 334 generates an output image by cropping the area indicated by the dashed line from the corrected image. In the second mode, multiple documents of equal width are placed on the document tray 11, and the left and right edges of the documents abut against the side guide plate 42, resulting in small skew and resist misalignment, and thus small document loss, which enables the cropping described above.

[0124] Figure 23 is a flowchart showing an example of the procedure for generating an output image according to the third embodiment. First, the outline detection unit 331 detects the outline of the original document, and the size detection unit 333 detects the size of the original document (step S301).

[0125] If the shape detection unit 331 successfully detects the shape (step S302: Yes), the correction image generation unit 332 corrects the read image (step S303). On the other hand, if the shape detection unit 331 fails to detect the shape (step S302: No), the correction image generation unit 332 outputs the read image as a corrected image (step S306).

[0126] Next, if the mode setting unit 321 is set to the first mode (step S304: Yes), the output image generation unit 334 extracts the output image from the corrected image (step S305). On the other hand, if the mode setting unit 321 is set to the second mode (step S304: No), the output image generation unit 334 outputs the corrected image as the output image (step S307).

[0127] Thus, according to this embodiment, a high-quality image can be generated by using a scanned image without any missing parts of the original document to detect the outline and size of the original document, correcting for skew and registration, and cropping the output image. Furthermore, even if the detection of the outline fails, an output image without any missing parts of the original document can be generated.

[0128] In the embodiments described above, the image forming apparatus of the present invention was explained using examples of its application to a multifunction device having at least two functions from among a copy function, a printer function, a scanner function, and a facsimile function. However, it can be applied to any image forming apparatus such as a copier, printer, scanner, or facsimile device.

[0129] In the above description, the image processing unit 200 is assumed to be included in the image forming apparatus 100, but the image processing unit 200 may be provided in an external device (external device) outside of the image forming apparatus 100. In this case, the external device is connected to the scanner 101 and the ADF 102 so as to be able to communicate with each other.

[0130] The programs executed by the image reading devices of each embodiment described above are provided as installable or executable files recorded on computer-readable recording media such as CD-ROMs, flexible disks (FDs), CD-Rs, and DVDs (Digital Versatile Disks).

[0131] Furthermore, the program executed by the image reading device of each embodiment may be stored on a computer connected to a network such as the Internet and provided by downloading it via the network. Alternatively, the program executed by the image reading device of each embodiment may be provided or distributed via a network such as the Internet.

[0132] Furthermore, the programs for each embodiment may be pre-installed and provided in ROM or the like.

[0133] The program executed in the image reading device of each embodiment has a modular configuration that includes the above-mentioned parts (maximum size setting unit 301, reading area setting unit 302, image reading unit 303, etc.), and in actual hardware, the CPU (processor) reads the program from the recording medium and executes it, thereby loading the above-mentioned parts onto the main memory and generating the program.

[0134] Each function of the embodiments described above can be realized by one or more processing circuits. Hereinafter, "processing circuit" as used herein includes processors programmed to execute each function by software, such as processors implemented by electronic circuits, as well as devices such as ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), FPGAs (Field Programmable Gate Arrays), and conventional circuit modules designed to execute each function described above.

[0135] Although various embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These novel embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. Furthermore, components from different embodiments and modifications may be combined as appropriate.

[0136] Examples of the present invention are as follows: <1> A maximum size setting unit that sets the maximum size including the maximum width and maximum length of multiple objects to be transported, A reading area setting unit sets the length of the reading area, which is the reading length required to read the object to be transported, and a first length, which is the reading length required to read the object downstream from the leading edge in the transport direction, according to the maximum size set by the maximum size setting unit. A target detection unit that detects the leading edge of the object being transported, An image reading unit starts reading from a position downstream in the transport direction by a first length from the tip detected by the target detection unit, and stops reading the image when the read length becomes the length of the reading area. This is an image reading device characterized by being equipped with [a specific feature]. <2> The aforementioned reading area setting unit is, The first length is set to a value independent of the maximum size, The length of the reading area is set to a value corresponding to the maximum size. <1> This is the image reading device described in [reference]. <3> The aforementioned reading area setting unit is, The first length is set to a value corresponding to the maximum size, The length of the reading area is set to a value corresponding to the maximum size. <1> This is the image reading device described in [reference]. <4> The system further includes a mode setting unit that sets either a first mode in which the width of at least one of the plurality of transported objects is different from the width of the other transported objects, or a second mode in which the widths of all of the plurality of transported objects are equal. The reading area setting unit sets the reading length required to read the object to be transported according to the mode set by the mode setting unit. <1> or <2> This is the image reading device described in [reference]. <5> The aforementioned object detection unit further detects the rear end of the object being transported, When the mode setting unit sets the first mode, The reading area setting unit sets the first length and the length of the reading area, The image reading unit starts reading from a position downstream in the transport direction by a first length from the leading edge of the transported object, and stops reading the image when the read length reaches the length of the reading area. When the mode setting unit sets the second mode, The reading area setting unit sets a second length which is the reading length downstream in the transport direction from the leading edge of the transported object, and a third length which is the reading length upstream in the transport direction from the rear end of the transported object. The image reading unit starts reading from a position downstream in the transport direction by a second length from the leading edge of the transported object, and ends reading from a position upstream in the transport direction by a third length from the rear end of the transported object. <4> This is the image reading device described in [reference]. <6> An external shape detection unit detects the external shape of the object to be transported and outputs a success / failure signal indicating whether the external shape detection was successful and an external shape signal indicating the external shape. A correction image generation unit generates a correction image based on the success / failure signal output by the external shape detection unit, the external shape signal, and the image read by the image reading unit. A size detection unit for detecting the size of the object to be transported, An output image generation unit generates an output image from the corrected image based on the mode set by the mode setting unit and the size of the object to be transported detected by the size detection unit, The aforementioned further comprising <4> or <5> This is the image reading device described in [reference]. <7> The corrected image generation unit, If the mode is the first mode, If the success / failure signal indicates that the detection of the external shape has been successful, the output image is generated from the corrected image by cropping based on the size of the object to be transported; if the success / failure signal indicates that the detection of the external shape has not been successful, the corrected image is generated as the output image. When the mode is the second mode, regardless of the success or failure signal, the output image is generated from the corrected image by cropping based on the size of the object to be transported. <6> This is the image reading device described in [reference]. <8> The external shape of the object to be transported is the inclination of the object to be transported or the resist, <6> or <7> This is the image reading device described in [reference]. <9> The corrected image generation unit, If the success / failure signal indicates that the detection of the external shape has been successful, the corrected image is generated from the read image by correction based on the external shape signal. If the success / failure signal indicates that the detection of the external shape was unsuccessful, the read image is generated as the correction image. <6> ~ <8> The image reading device is one of the devices described in any one of the following. <10> The reading area setting unit sets at least one of the length of the reading area and the first length according to the transport speed of the object being transported. <1> ~ <9> The image reading device is one of the devices described in any one of the following. <11> The reading area setting unit sets at least one of the length of the reading area, the first length, the second length, and the third length according to the transport speed of the object being transported. <5> This is the image reading device described in [reference]. <12> The maximum size setting unit sets the maximum width and the maximum length based on the output of a first sensor that detects the width of the object to be transported and the output of a second sensor that detects the length of the object to be transported. <1> ~ <11> The image reading device is one of the devices described in any one of the following. <13> The aforementioned <1> ~ <12> An image reading device described in any one of the following, An image forming unit that forms an image on a medium based on the image read by the aforementioned image reading device, This is an image forming apparatus having [a specific feature / feature]. <14> An image reading method performed by an image reading device, A maximum size setting step that sets the maximum size including the maximum width and maximum length of multiple objects to be transported, A reading area setting step sets the length of the reading area, which is the reading length required to read the object to be transported, and a first length, which is the reading length required to read the object downstream from the tip of the object in the transporting direction, according to the maximum size set in the maximum size setting step. A target detection process that detects the leading edge of the object being transported, An image reading step which starts reading from a position downstream in the transport direction by a first length from the tip detected by the target detection step, and ends reading the image when the length read reaches the length of the reading area, This is an image reading method characterized by including [a specific feature]. [Explanation of symbols]

[0137] 11. Document tray 42 Side guide plate 81 Resist Sensor 82 Document Set Sensor 83 Paper output sensor 84 sensors 85 Document width sensor 89 Main scanning sensor 90 Sub-scanning sensor 100 Image forming apparatus 101 Scanner 102 Automatic Document Feeder (ADF) 120 plotters 200 Image Processing Unit 301 Maximum size setting section 302 Reading Area Setting Unit 303 Image reading unit 321 Mode setting section 331 External shape detection unit 332 Correction Image Generation Unit 333 Size detection unit 334 Output Image Generation Unit [Prior art documents] [Patent Documents]

[0138] [Patent Document 1] Japanese Patent Publication No. 2010-141509

Claims

1. A maximum size setting unit that sets the maximum size including the maximum width and maximum length of multiple objects to be transported, A reading area setting unit sets the length of the reading area, which is the reading length required to read the object to be transported, and a first length, which is the reading length required to read the object downstream from the leading edge in the transport direction, according to the maximum size set by the maximum size setting unit. A target detection unit that detects the leading edge of the object being transported, An image reading unit starts reading from a position downstream in the transport direction by a first length from the tip detected by the target detection unit, and stops reading the image when the read length becomes the length of the reading area. An image reading device characterized by comprising the following:

2. The aforementioned reading area setting unit is, The first length is set to a value independent of the maximum size, The image reading device according to claim 1, wherein the length of the reading area is set to a value corresponding to the maximum size.

3. The aforementioned reading area setting unit is, The first length is set to a value corresponding to the maximum size, The image reading device according to claim 1, wherein the length of the reading area is set to a value corresponding to the maximum size.

4. The system further includes a mode setting unit that sets either a first mode in which the width of at least one of the plurality of transported objects is different from the width of the other transported objects, or a second mode in which the widths of all of the plurality of transported objects are equal. The image reading device according to claim 1, wherein the reading area setting unit sets the reading length required for reading the object to be transported according to the mode setting unit.

5. The aforementioned object detection unit further detects the rear end of the object being transported, When the mode setting unit sets the first mode, The reading area setting unit sets the first length and the length of the reading area, The image reading unit starts reading from a position downstream in the transport direction by a first length from the leading edge of the transported object, and stops reading the image when the read length reaches the length of the reading area. When the mode setting unit sets the second mode, The reading area setting unit sets a second length which is the reading length downstream in the transport direction from the leading edge of the transported object, and a third length which is the reading length upstream in the transport direction from the rear end of the transported object. The image reading device according to claim 4, wherein the image reading unit starts reading from a position downstream in the transport direction by a second length from the leading edge of the transported object, and ends reading from a position upstream in the transport direction by a third length from the rear end of the transported object.

6. An external shape detection unit detects the external shape of the object to be transported and outputs a success / failure signal indicating whether the external shape detection was successful and an external shape signal indicating the external shape. A correction image generation unit generates a correction image based on the success / failure signal output by the external shape detection unit, the external shape signal, and the image read by the image reading unit. A size detection unit for detecting the size of the object to be transported, An output image generation unit generates an output image from the corrected image based on the mode set by the mode setting unit and the size of the object to be transported detected by the size detection unit, The image reading device according to claim 4, further comprising the above.

7. The corrected image generation unit, If the mode is the first mode, If the success / failure signal indicates that the detection of the external shape has been successful, the output image is generated from the corrected image by cropping based on the size of the object to be transported; if the success / failure signal indicates that the detection of the external shape has not been successful, the corrected image is generated as the output image. The image reading device according to claim 6, wherein, when the mode is the second mode, the output image is generated from the corrected image by cropping based on the size of the object to be transported, regardless of the success or failure signal.

8. The image reading device according to claim 6, wherein the external shape of the object to be transported is the inclination of the object to be transported or a resist.

9. The corrected image generation unit, If the success / failure signal indicates that the detection of the external shape has been successful, the corrected image is generated from the read image by correction based on the external shape signal. The image reading device according to claim 6, wherein the read image is generated as the correction image when the success / failure signal indicates that the detection of the external shape has not been successful.

10. The image reading device according to claim 1, wherein the reading area setting unit sets at least one of the length of the reading area and the first length according to the transport speed of the transported object to be transported.

11. The image reading device according to claim 5, wherein the reading area setting unit sets at least one of the length of the reading area, the first length, the second length, and the third length according to the transport speed of the object being transported.

12. The image reading device according to claim 1, wherein the maximum size setting unit sets the maximum width and the maximum length based on the output of a first sensor that detects the width of the object to be transported and the output of a second sensor that detects the length of the object to be transported.

13. An image reading device according to any one of claims 1 to 12, An image forming unit that forms an image on a medium based on the image read by the aforementioned image reading device, An image forming apparatus having

14. An image reading method performed by an image reading device, A maximum size setting step that sets the maximum size including the maximum width and maximum length of multiple objects to be transported, A reading area setting step sets the length of the reading area, which is the reading length required to read the object to be transported, and a first length, which is the reading length required to read the object downstream from the tip of the object in the transporting direction, according to the maximum size set in the maximum size setting step. A target detection process that detects the leading edge of the object being transported, An image reading step which starts reading from a position downstream in the transport direction by a first length from the tip detected by the target detection step, and ends reading the image when the length read reaches the length of the reading area, An image reading method characterized by including [a certain element].

Images