Image reading device and image reading control method

Abstract

To achieve both of a processing speed and a cost burden related to processing of blank determination within a reasonable range even if a document is in an indefinite size.SOLUTION: An image reader comprises: a document size detection unit which detects any of vertical and horizontal lengths of a document fed by a document feeder before reading and links the length to a corresponding or approximate definite size; an image reading device which reads the document and the periphery thereof at the reading position; a background color plate which is read as the image of the periphery; a document area determination unit which distinguishes the contour of the document to determine a document area on the basis of a density difference or color difference between the read document and the background color plate; and a blank determination unit which determines a blank determination area for determining whether or not the document is blank. The blank determination unit determines the blank determination area using the linked definite size as a reference in a case where any of the vertical and horizontal lengths of the detected document is equal to or greater than a predetermined threshold, and determines the blank determination area using the document area as a reference in a case where the length is in a size equal to or less than the threshold.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an image reading apparatus and a method for controlling image reading. More specifically, the present invention relates to an image reading apparatus and a method for controlling image reading, which have a function of discriminating the outline of a document based on the density difference or color difference between the document and its surroundings and determining the document area.

Background Art

[0002] In image reading apparatuses such as multifunction devices and image scanners, as a mode of reading a document, there are often a mode of scanning a document placed on a document table (platen mode) and a mode of transporting and reading a document by a document feeder (SPF (Single Pass Feeder) mode). In both cases, it is normal to detect the document size and read the area excluding the margins of the document area. The document sizes that can be detected by an image reading apparatus are usually limited to so-called standard sizes such as A3, A4, A5, 11”×17”, 8.5”×11”, 5.5”×8.5”, etc. To read a non-standard size (irregular size), means for manually inputting the vertical and horizontal sizes of the document are provided.

[0003] Even if it is rare to read a document of an irregular size, manually inputting the document size at that time is cumbersome. If the exact document size can be detected even for an irregular size, the trouble of complicated input can be saved, which is convenient. As a means of enabling the detection of the exact manuscript size even for an irregular size, there is a method of setting the background color plate at the position where the manuscript is read in the SPF mode to a color different from white (e.g., gray), which is the ground color of a general manuscript, and determining the outline of the manuscript from the image of the background color plate that appears around the manuscript and the manuscript. An area inside by a predetermined distance from the detected outline of the manuscript is cropped and output. This assumes that the ground color of a general manuscript is white, and discriminates the outline of the manuscript based on the density difference or color difference between the ground color (white) at the edge of the manuscript and the color of the background color plate (e.g., gray). In this way, the function of determining and cropping the outline of the manuscript based on the density difference or color difference from the surroundings is called the SPF crop function in this specification, and the mode using the SPF crop function is called the SPF crop mode.

[0004] However, when reading a manuscript with a light white background using a background color plate other than white (e.g., gray), the color of the background color plate may appear somewhat transparent, and as a result, the background of the read manuscript image may be colored. Therefore, there is also a method of dividing the background color plate into a white area and a gray area, and switching the reading position between the area other than white and the white area depending on whether the manuscript is of an irregular size or a mixed-loaded manuscript or not.

[0005] In addition, there is a mode in which a manuscript reading device reads a multi-page manuscript and removes blank pages among them. To determine whether each page of the manuscript is blank, a blank page determination area inside the edge of the manuscript is determined, and it is determined by hardware processing or software processing whether there are a predetermined number or more of black pixels or color pixels other than the background (white pixels) in the blank page determination area. Since areas outside or at the edge of the manuscript usually contain non-white pixels such as the shadow of the manuscript, the determination is made in the inner blank page determination area as described above. For accurate blank page determination, it is essential to correctly detect the blank page determination area, and to correctly detect the blank page determination area, it is essential to correctly detect the area inside the edge of the manuscript, that is, the manuscript area. However, as described above, the types of sizes that can be detected by a manuscript feeding device or the like are usually limited to regular sizes, and it is not possible to accurately detect an irregular size manuscript. The present invention relates to a process of discriminating the outline of a manuscript in the SPF crop mode and performing a blank paper determination in an area based on the outline.

[0006] Although it is a different matter from the SPF crop function, regarding the detection of the blank paper determination area and the removal of the blank paper image, there is known an image reading apparatus that repeatedly detects whether or not a page is a blank paper for each blank paper detection area of each page in the case of a mixed manuscript. The main scanning detection sensor on the manuscript conveyance path detects the size of the manuscript in the main scanning direction (a direction perpendicular to the manuscript conveyance direction) of the manuscript fed one by one onto the manuscript conveyance path by the manuscript supply roller, and obtains the standard size of that page. Here, the main scanning detection sensor is composed of sensors that detect the presence or absence of a plurality of (for example, about 4 to 10) manuscripts along the main scanning direction. Then, a range that is a predetermined distance inward from the end of the standard size of the detected manuscript in the sub-scanning direction is set as a blank paper detection area for detecting whether or not it is a blank paper. Detection of whether or not it is a blank paper is repeated in units of bands within the range of the sub-scanning width of the blank paper detection area. By performing the blank paper determination in units of bands, even when continuously reading manuscripts one by one from a bundle of manuscripts with different sizes mixed, the blank paper determination can be performed without reducing the reading speed (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] Patent Document 1 relates to a method for performing a blank paper determination of a mixed manuscript without reducing the reading speed, but it assumes a manuscript of a standard size, and no configuration corresponding to an irregular size is described. If the size of the original document can be determined before reading each page of the original document, for white page determination, for example, a rectangular area (white page determination area) that is a predetermined amount inside the original document area of a known size can be set in the register, and the black pixels (color pixels) within the white page determination area can be counted. Such an image processing circuit can be realized with a relatively simple configuration. However, providing means for detecting the size of the original document including an irregular size before reading the original document is a significant cost burden considering the frequency of use of irregular sizes. For example, to improve the detection accuracy of an irregular size with the configuration of the main scanning detection sensor in Patent Document 1, it is necessary to considerably increase the number of sensors.

[0009] The above-mentioned SPF crop function determines the outline of the original document based on the density difference (color difference) between the read original document and the surrounding image. Therefore, even for an irregular size, the size of the original document can be accurately detected, and the white page determination area can be cropped based on the detected outline of the original document. Compared with a configuration that separately provides means for detecting the size of the original document including an irregular size to determine the size of the original document, there is no or only a slight cost burden. Instead, in the SPF crop function, since the size of the original document is determined after reading each page of the original document, it takes time to determine the white page determination area. The greater the size of the original document, the greater the time difference between the two. The present invention has been made in consideration of the above circumstances, and even for an original document of an irregular size that the original document size detection unit cannot handle, it makes the processing speed and cost burden related to the white page determination process compatible within a reasonable range.

Means for Solving the Problem

[0010] The present invention relates to a document feeder that feeds one or more documents placed at a placement position to a reading position one by one, a document size detection unit that detects at least one of the vertical and horizontal lengths of the fed document before reading and associates a corresponding or approximate standard size among a plurality of standard sizes with a predetermined length in both vertical and horizontal directions, an image reading device that reads a document and its surroundings as an image at the reading position, a background color plate arranged so as to be read by the image reading device as an image of the surroundings, a document area determination unit that determines a document area by discriminating the outline of the document based on the density difference or color difference between the document and the background color plate in the read image, and a blank determination unit that determines a blank determination area for determining whether the read document is a blank sheet. The blank determination unit determines the blank determination area based on the standard size associated by the document size detection unit when at least one of the vertical and horizontal lengths of the document detected by the document size detection unit is equal to or larger than a predetermined threshold size, and determines the blank determination area based on the document area when the size is less than the threshold size. An image reading apparatus is provided.

[0011] Also, from a different perspective, the present invention provides a method for controlling image reading, in which a computer includes steps of feeding one or more documents to a reading position one by one, detecting at least one of the vertical and horizontal lengths of the fed document before reading and associating a corresponding or approximate standard size among a plurality of standard sizes with a predetermined length in both vertical and horizontal directions, reading the document as an image together with a background color plate that exposes the document at the reading position, determining a document area by discriminating the outline of the document based on the density difference or color difference between the document and the background color plate in the read image, and determining a blank determination area for determining whether the read document is a blank sheet. When at least one of the vertical and horizontal lengths of the detected document is equal to or larger than a predetermined threshold size, the blank determination area is determined based on the standard size associated with the document, and when the size is less than the threshold size, the blank determination area is determined based on the document area.

Advantages of the Invention

[0012] In the image reading apparatus according to the present invention, when at least one of the vertical and horizontal lengths of the document detected by the document size detection unit is equal to or greater than a predetermined threshold value, the blank page determination unit determines the blank page determination area based on the standard size associated with the document size detection unit. When the size is less than the threshold value, the blank page determination area is determined by the SPF crop function based on the document area. Therefore, it is possible to balance the processing speed and cost burden related to the blank page determination for documents of irregular sizes within a reasonable range. The image reading control method according to the present invention also has the same operational effects.

Brief Description of the Drawings

[0013]

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[0014] Hereinafter, the present invention will be described in more detail with reference to the drawings. It should be noted that the following description is illustrative in all respects and should not be construed as limiting the present invention. (Embodiment 1) ≪Configuration of Image Reading Apparatus≫ First, the image reading apparatus in this embodiment will be described. FIG. 1 is a perspective view showing a part of the appearance of a multifunction machine as an aspect of the image reading apparatus in this embodiment. It shows the part related to document reading. FIG. 2 is a block diagram showing the overall configuration of the multifunction machine shown in FIG. 1. As shown in the block diagram of FIG. 2, the multifunction machine 100 includes a control unit 11, a storage device 13, an engine unit 14 for forming an image, a scanner unit 15, and a UI display unit 19 (also referred to as a user interface display unit). The control unit 11 includes a display control unit 11U, a file control unit 11F, a job management unit 11J, a job execution unit 11X, an image processing unit 11P, and a communication unit 11C. The control unit 11 controls the multifunction machine 100. The image processing unit 11P includes an input processing unit 41, a blank paper determination unit 43, a document area determination unit 45, and an output image generation unit 47.

[0015] The UI display unit 19 is configured by, for example, a liquid crystal display device and displays a screen according to the control of the display control unit 11U. The UI display unit 19 also includes an operation input device such as a touch panel and is provided on the housing of the multifunction machine 100 as shown in FIG. 1. The operation input device detects the user's operation on the UI display unit 19, and the display control unit 11U recognizes the signal of the operation detected by the operation input device. The file control unit 11F performs operations such as saving and reading files to and from the storage device 13, and expanding files to the storage device 13.

[0016] The job management unit 11J performs processes such as registration, deletion, and stop of various jobs such as copy jobs, scanner jobs, or print jobs. When the job registered in the job management unit becomes executable, the job management unit 11J requests the job execution unit 11X to start executing the job. The job execution unit 11X determines whether to start executing the job registered by the job management unit 11J, and causes the engine unit 14, the scanner unit 15, and the image processing unit 11P to execute jobs according to the settings. The job execution unit 11X recognizes the states detected by sensors (not shown) arranged in the scanner unit 15 and the engine unit 14. Then, it controls the operations of motors, actuators, devices, etc. (not shown) arranged in the scanner unit 15 and the engine unit 14. Also, the image processing unit 11P controls the processing related to the image of the image processing unit 11P. And it executes processes related to jobs such as reading, printing, and previewing the image of the original document.

[0017] The control unit 11 is configured mainly around a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) as a specific configuration mode. In addition to the processor, it is composed of hardware resources such as a work memory, an input / output interface circuit, a timer circuit, an image processing circuit, and a communication circuit. By the processor executing the control program stored in advance in the storage device 13, it executes various jobs related to operation recognition, display control, reading of the original image, printing of the image, etc., that is, a series of processes related to image formation. The software resources and the hardware resources cooperate to realize the functions of the control unit 11.

[0018] The storage device 13 includes a volatile memory such as a DRAM and a non-volatile memory such as an HDD or a flash memory. The storage device 13 stores a control program executed by the processor, images read by the scanner unit 15, and processed by the image processing unit 11P. Further, it stores data related to the control of the file control unit 11F, the job management unit 11J, the job execution unit 11X, and the image processing unit 11P. The storage device 13 may be configured integrally with the memory of the control unit 11.

[0019] The control unit 11 and the engine unit 14, and the control unit 11 and the scanner unit 15 are connected so as to be able to transfer data to each other. The communication unit 11C includes a circuit for performing data communication with external devices via a network. As shown in FIG. 1, the multifunction device 100 includes a document feeder 16 (also referred to as an SPF or a Single Pass Feeder). Since the document feeder 16 reads documents in cooperation with the scanner unit in the SPF mode, it is shown as being included in the scanner unit 15 in FIG. 3. FIG. 3 is an explanatory diagram showing the schematic configuration of the scanner unit 15 and the document feeder 16 of the multifunction device 100 shown in FIG. 1. As shown in FIG. 3, the scanner unit 15 is composed of a transparent glass plate on the upper side and includes a document table 17 on which a document to be read in the platen mode is placed. An SPF reading window 18 is arranged adjacent to the left end of the document table 17. The SPF reading window 18 is composed of a transparent glass plate similar to the document table 17. The SPF 16 can be opened upward so that the document table 17 is exposed, and a background color plate 51 is arranged on the bottom surface of the SPF 16. In the state where the SPF 16 is closed, the background color plate 51 faces the lower SPF reading window 18.

[0020] The scanner unit 15 reads the image of the document under the control of the job execution unit 11X and converts it into an image signal (RGB analog signal). That is, it executes the image reading process in the jobs of copy, fax, and scanner. In the SPF mode, the SPF16 shown in FIG. 3 separates and feeds the originals one by one from the stack of originals set at the placement position of the original set tray 31 (see arrow IN shown in FIG. 3), conveys the originals via the reading positions R1 and R2, and discharges them to the original discharge tray 33 (see arrow OUT shown in FIG. 3).

[0021] The original set tray 31 has an original guide 35 whose width in the main scanning direction perpendicular to the original feeding direction can be adjusted, and an original sensor 37 that detects the presence or absence of an original at a plurality of positions in the sub-scanning direction along the feeding direction. The control unit 11 recognizes the position of the original guide 35 and the presence or absence of an original at each position by the original sensor 37, and determines the size of the original set on the original set tray 31. The original guide 35 and the original sensor 37 correspond to the original size detection unit. The original guide 35 can detect the length of the original in the main scanning direction with an error of 1 mm or less in one example. The original sensor 37 detects the presence or absence of an original at positions corresponding to the types of standard sizes. A conveyance path sensor 39 that detects the passage of the fed original is arranged in the middle of the conveyance path from the original set tray 31 to the reading position R1. The conveyance path sensor 39 has a plurality of photosensors arranged in the main scanning direction, and each photosensor detects the original passing through its position, and corresponds to the original size detection unit. Thereby, the standard size of the passing original in the main scanning direction can be detected. However, it is not always possible to detect the rear end of the original before its front end reaches the reading position R1 or R2. That is, it is not always possible to detect the length of the original in the sub-scanning direction before reading. Therefore, the original size detection unit can detect standard-size originals before reading, but cannot detect the sizes of non-standard-size originals.

[0022] By moving the position of the control unit 11 of the first carriage, the reading position of the document in the SPF mode can be switched between the normal reading position R1 and the reading position R2 in the SPF crop mode (see Fig. 3). In this embodiment, the area of the background color plate 51 read by the scanner unit 15 at the reading position R1 is white, which is the same color as the background color of a general document, and the color of the background color plate 51 read by the scanner unit 15 at the reading position R2 is gray, which is different from the background color of a general document. Both the reading positions R1 and R2 are located at positions sandwiched between the lower SPF reading window 18 and the upper background color plate 51. The document being conveyed passes in front of the background color plate 51 at the reading positions R1 and R2.

[0023] The scanner unit 15 reads the document passing through at the reading position R1 or R2. For the part where there is no document, it reads the background color plate 51. The first carriage 55 is equipped with an LED and a reflection mirror for irradiating the document surface, and the second carriage 57 is equipped with two reflection mirrors. The image of the document passing through the reading position R1 or R2 forms an image on the image sensor 61 through those reflection mirrors and the optical lens 59. Note that the first carriage can also move downward the document table 17. In the platen mode, the document placed on the document table 17 is scanned from below to read the document. When the first carriage 55 moves, the second carriage 57 moves in the same direction at half the speed of the first carriage 55 to form an image of the document placed on the document table 17 on the image sensor 61. The image sensor outputs an image signal corresponding to the document image.

[0024] The image processing unit 11P generates image data based on the image signal output by the scanner unit 15. Alternatively, it generates print image data based on the print data received via the communication unit 11C. The image processing unit 11P controls those processes of the image processing unit 11P. The generated image data is grouped into image files in units corresponding to the stacks of originals. The file control unit 11F performs processes for generating and managing image files from the image data and controls the reading and writing of the image files. The image files are printed by the engine unit 14 or transmitted to external devices via the communication unit 11C.

[0025] The input processing unit 41 of the image processing unit 11P shown in FIG. 2 receives an image signal from the image sensor 61 of the scanner unit 15 and performs image processing. Then, it generates an image that serves as the basis for the image for determining the original area and the output image. The input processing unit 41 includes circuits for performing A / D conversion, shading correction, gradation conversion, etc. of the image signal. The blank page determination unit 43 is a circuit block that counts the ratio of black pixels included in the blank page determination area among the page-by-page image signals received from the scanner unit 15 to determine a blank page. The determination result is provided to the output image generation unit 47 and used for control to suppress the output of blank pages. The blank page determination area is an area located a predetermined length inside from the edge of the original, that is, an area obtained by cropping the original.

[0026] The original document area determination unit 45 is a circuit block that determines the original document area of the read image based on the determination image output from the input processing unit 41. In the SPF crop mode for determining the original document area of an irregular size, the original document area determination unit 45 determines a rectangular original document area based on the density difference or color difference between the edge of the original document and the gray color of the background color plate 51. The determination of the original document area is to determine the contour of the rectangular original document. For the purpose of simplifying the process, as the determination image, for example, an image obtained by reducing the resolution of the read image and performing binary black-and-white conversion may be used. Note that the original document area determination unit 45 may not only detect the contour of the original document when determining the rectangular original document area, but also perform character recognition processing to detect the inclination and top-bottom of the target page of the original document. Then, the original document area may be determined in consideration of the inclination and top-bottom of the target page. The determined original document area is provided to the output image generation unit 47 and used for the crop processing of the output image.

[0027] The output image generation unit 47 further performs image processing on the output image output from the input processing unit 41 and generates an image file in the format to be output. The image processing performed by the output image generation unit 47 includes the process of skipping blank pages based on the determination result of the blank page determination unit 43. Further, it includes the crop processing of each page based on the original document area determined by the original document area determination unit 45. This crop processing is a different process from the crop processing when obtaining the blank page determination area and is the crop processing when obtaining the output image. In addition, the image processing by the output image generation unit 47 may include image quality adjustment, color correction, spatial filter processing, displacement processing, etc. For example, when transmitting the image of the read original document as an image file in the PDF (Portable Document File) format to a specified destination via the communication unit 11C, the output image generation unit 47 generates an image file in the PDF format from the image data of each page. Then, the generated image file in the PDF format is output.

[0028] <<Example of Reading an Original Document and Performing Blank Page Skipping Processing Based on Blank Page Determination>> Subsequently, an example of blank page determination according to this embodiment and blank page skipping based on it is shown. FIG. 4 and FIG. 5 are explanatory diagrams showing examples of reading a document and performing blank page skipping processing when the SPF crop mode is effective in this embodiment. Both are examples of mixed documents, where the first page is a blank page and the second page is an example of reading a non-blank document. In contrast, FIGS. 6 and 7 show examples of reading a mixed document without using SPF crop and performing blank page skipping processing. FIG. 6 shows cases where both the first and second pages are documents of a standard size, and FIG. 7 shows the case where the first page is a document of a non-standard size.

[0029] In FIG. 4, the length in the main scanning direction detected by the document guide 35 is a size equal to or less than a predetermined threshold value. In contrast, in FIG. 5, the length in the main scanning direction detected by the document guide 35 is a size larger than the aforementioned threshold value. An example of the threshold value is a length of 140 mm. In the cases of FIGS. 4 and 5, it is assumed that the control unit 11 controls the scanner unit 15 to perform reading in the SPF crop mode as the job execution unit 11X. The document 21 fed on the first page is a document having a size smaller than the width of the document guide 35, but the control unit 11 causes the scanner unit 15 to read a region in the main scanning direction that is slightly larger than the width of the document guide 35 as the input processing unit 41.

[0030] Note that since the conveyance path sensor 39 detects the standard size of the document 21 in the main scanning direction before reading, the scanner unit 15 may be caused to read a region in the main scanning direction that is slightly larger than the width of the detected standard size. However, in any case, a process of cropping the document region 26 from the read image 24 is involved. In the sub-scanning direction, the scanner unit 15 is caused to read a region in the sub-scanning direction that is slightly larger than the lengths of the leading and trailing ends of the document detected by the conveyance path sensor 39. As described above, the read image 24 shown in gray in FIGS. 4 and 5 corresponds to a region where the main scanning direction corresponds to the width of the document guide 35 and the sub-scanning direction is slightly larger than the leading and trailing ends of the document, respectively. The read image 24 has the document region of the document 21 surrounded by the gray region of the background color plate 51. The same applies to the read image 24 of the document 22.

[0031] As the original document area determination unit 45, the control unit 11 determines the original document areas 26 of the original documents 21 and 22 by discriminating the density difference or color difference between the ground color of the original document of the read image 24 in the SPF crop mode and the surrounding background color plate 51. As the blank paper determination unit 43, the control unit 11 determines the blank paper determination areas 28 corresponding to the original documents 21 and 22 as the areas obtained by cropping the read image 24 based on the original document area 26 thus obtained. The blank paper determination areas 28 are shown hatched in FIGS. 4 and 5. The blank paper determination area 28 is an area that is inward by a predetermined distance (in one example, 2 mm inward from each of the four sides of the original document area) from the four sides of the original document area. As the blank paper determination unit 43, the control unit 11 determines that the page is blank if the number of black pixels (color pixels) in the blank paper determination area is less than the reference number, and determines that it is not blank otherwise. In the examples shown in FIGS. 4 and 5, it is assumed that the first original document 21 is blank and the second original document 22 is not blank, and correct blank paper determination results are expected.

[0032] Reading in the SPF crop mode as shown in FIGS. 4 and 5 can accurately determine the original document size even for original documents of irregular sizes. Furthermore, even when the original document is slightly skewed, the outline of the original document can be accurately discriminated. However, the crop processing of the read image 24 is essential. Therefore, there is an aspect that it takes time for the processing until the result of the blank paper determination is obtained. The processing time until the result of the blank paper determination is obtained depends on the original document size, and the larger the original document, the longer the processing time required. The required time for the blank paper determination process may affect not only the time until the file output but also the user's operation related to the preliminary confirmation of the file output. That is, it is also a matter related to the operability of the image reading device.

[0033] According to this embodiment, if the length of the document in the main scanning direction (the width of the document) detected by the document guide 35 before reading is a small document with a length equal to or less than a threshold value (140 mm in one example), the control unit 11 reads the document in the SPF crop mode. When the width of the document guide 35 is equal to or less than the threshold value, the time required for the crop process and the blank paper determination process after the crop process is shorter than that for a document with a size larger than the threshold value. Therefore, the difference in processing time from reading without using the SPF crop mode is small. In addition, there is a high possibility that receipts or business cards are set, and since they usually belong to documents of irregular sizes, it is reasonable to read them in the SPF crop mode.

[0034] On the other hand, in the case of a large document whose width exceeds the threshold value, the control unit 11 reads the document without using the SPF crop mode. Large-sized documents are often of regular sizes. Therefore, the crop process of the read image is omitted. By determining the blank paper determination area based on the document size detected before reading and performing the blank paper determination, the processing time can be shortened compared to reading in the SPF crop mode. As will be described later in Embodiment 2, it is also possible to determine whether the size of the document placed on the document set tray 31 (the document size detected by the document guide 35 and the document sensor 37) is a regular size or an irregular size, and switch whether to read in the SPF crop mode according to the determination.

[0035] FIGS. 6 and 7 are examples of reading mixed documents without using SPF crop. FIG. 6 shows an example in which the width of the document detected by the document guide 35 is within a predetermined range (for example, a range of ±1 mm) with respect to a predetermined length corresponding to a regular size. Here, the predetermined length refers to, for example, 297 mm and 210 mm corresponding to the vertical and horizontal dimensions of the A4 size, 257 mm and 182 mm corresponding to the vertical and horizontal dimensions of the B5 size, etc., that is, the length of either the vertical or horizontal dimension of a so-called regular size. Not limited to the AB series, it may include inch-based sizes such as 279.4 mm and 215.9 mm corresponding to the vertical and horizontal dimensions of the letter size. On the other hand, FIG. 7 shows an example in which the width of the document detected by the document guide 35 is not within the predetermined range with respect to the predetermined length.

[0036] As shown in FIGS. 6 and 7, when the width of the document detected by the document guide 35 is greater than the threshold value, the control unit 11 as the job execution unit 11X controls the scanner unit 15 so as not to perform reading in the SPF crop mode. The document 21 fed first is a document having a size smaller than the width of the document guide 35. As the input processing unit 41 and the document area determination unit 45, the control unit 11 recognizes a predetermined length (a length corresponding to the vertical or horizontal of any standard size) detected by the conveyance path sensor 39 after feeding. Then, the scanner unit 15 is made to read an area corresponding to the predetermined length detected by the conveyance path sensor 39. In the sub-scanning direction, as the input processing unit 41 and the document area determination unit 45, the control unit 11 causes the scanner unit 15 to read an area in the sub-scanning direction corresponding to any standard size based on the lengths of the leading and trailing ends of the document detected by the conveyance path sensor 39.

[0037] For example, assume that the conveyance path sensor 39 determines that the length of the document in the main scanning direction is the long side of A4 or the short side of A3 after passing the leading end of the document. In that case, the length of the document in the sub-scanning direction is determined based on the detection by the conveyance path sensor 39. The read image 24 shown in FIGS. 6 and 7 shows an area of a standard size corresponding to the leading end and the trailing end of the document detected by the conveyance path sensor 39. The read image 24 obtained in this way corresponds to the document area of the document 21 without crop processing in the case of the standard size document shown in FIG. 6. Similarly, the read image 24 of the document 22 fed second also corresponds to the document area of the second document 22. In the case of a standard size document, crop processing after the read image 24 is obtained is not necessary.

[0038] In the case of the non-standard size document shown in FIG. 7, the read image 24 based on the detection of the standard size by the conveyance path sensor 39 is larger in the main scanning direction than the original document area of the document 21. As a result of rounding the non-standard size to a standard size close thereto, it includes an area other than the document 21. It is the gray area of the background color plate 51. However, since it is reading without using the SPF crop mode, the control unit 11 assumes that the read image is the document area of the document 21. As the blank paper determination unit 43, the control unit 11 determines a blank paper determination area 28 corresponding to the originals 21 and 22 based on the original area 26. As a result, the blank paper determination area 28 includes the gray area of the background color plate 51, and thus the blank paper determination unit 43 cannot perform correct blank paper determination.

[0039] The blank paper determination area 28 is shown hatched in FIG. 7. Note that the blank paper determination areas 28 shown in FIGS. 6 and 7 are both areas that are inward by a predetermined distance (in one example, 2 mm inward from each of the four sides of the original area) from the four sides of the original area 26. For an original of a standard size as shown in FIG. 6, it is assumed that the first original 21 is a blank paper and the second original 22 is not a blank paper, and correct results are expected. However, for an original of an irregular size as shown in FIG. 7, it is assumed that neither the first original 21 nor the second original 22 is a blank paper. For the first original 21 of an irregular size, correct results cannot be obtained.

[0040] (Embodiment 2) As described above, in Embodiment 1, when the width of the original is larger than the threshold value, reading without using the SPF crop mode is performed. Therefore, although the processing time for blank paper determination is shorter than that in the SPF crop mode, correct results may not be obtained for an original of an irregular size. In this embodiment, when the width of the original is larger than the threshold value, if the possibility of an original of an irregular size is high, priority is given to more accurate blank paper determination rather than the processing time. On the other hand, if the possibility of an original of a standard size is high, similar to Embodiment 1, reading without using the SPF crop mode is performed to give priority to shortening the processing time. Whether the possibility of an original of an irregular size is high or the possibility of an original of a standard size is high is determined based on the width of the original detected by the original guide 35 before reading. This is because in this embodiment, the original guide 35 can detect the size of the original including an irregular size before reading.

[0041] As the input processing unit 41 and the document area determination unit 45, when the width of the document detected by the document guide 35 is greater than the threshold value, the control unit 11 further determines whether it is within a predetermined range (for example, a range of ±1 mm) with respect to a predetermined length. When the width of the document is within the above range with respect to the predetermined length, it is determined that there is a high possibility of a regular-size document, and reading is performed without using the SPF crop mode as in the first embodiment. When there are mixed small documents of irregular sizes as shown in FIG. 7, accurate blank page determination may not be obtained. However, even if there is an error in the blank page determination, the misjudgment occurs on the safe side. That is, as is clear from the example of FIG. 7, even if a blank document is not excluded due to misjudgment, a non-blank document is not excluded due to misjudgment. In other words, the information that should originally exist is not missing due to misjudgment.

[0042] On the other hand, when the width of the document is outside the above range with respect to the predetermined length, it is determined that there is a high possibility of an irregular-size document, and reading is performed in the SPF crop mode. As shown in FIG. 5, if reading is performed in the SPF crop mode, an appropriate document area and blank page determination area can be determined even for an irregular-size document. Although it takes more processing time for blank page determination than in the SPF crop mode, correct results can be obtained.

[0043] (Embodiment 3) When the width of the document detected by the document guide 35 is greater than the threshold value, it may be possible to select by setting whether to perform reading without using the SPF crop mode uniformly as in the first embodiment or to switch the on / off of the SPF mode according to the relationship between the document width and the predetermined length as in the second embodiment. Furthermore, when the width of the document is greater than the threshold value, there may be an option to perform reading in the SPF crop mode uniformly.

[0044] The frequency (proportion) of reading manuscripts of irregular sizes depends on the manuscripts handled by the user, so appropriate operations can be set according to the usage situation. For users who rarely read manuscripts of irregular sizes, they can set to prioritize processing speed for manuscripts wider than the threshold as in Embodiment 1. For users who frequently read manuscripts of irregular sizes, they can set to perform reading in the SPF crop mode with priority given to accurate blank page determination even for manuscripts wider than the threshold. For users who are neither of the above, they can set to switch the on / off of the SPF crop mode according to the relationship between the manuscript width and the default length.

[0045] <<Flowchart of manuscript reading and blank page determination>> The processing of the control unit 11 described in Embodiments 1 and 2 will be described while referring to the flowchart. Figs. 8 to 10 are flowcharts showing the manuscript reading process executed by the control unit in Embodiments 1 and 2. As shown in Fig. 8, when the display control unit 11U receives an instruction to start manuscript reading from the user via the UI display unit 19 (Yes in step S11), the control unit 11 as the job execution unit 11X determines whether to read in the feeder mode or the platen mode (step S13). When reading in the platen mode (No in step S13), a scanner motor (not shown) is controlled to move the first carriage 55 to scan the platen 17, and the manuscript placed on the platen 17 is read. The output image generation unit 47 generates and outputs a file from the read image (step S15), and the process ends.

[0046] When reading in the feeder mode (Yes in step S13), the control unit 11 as the job execution unit 11X determines whether to read the manuscript in the SPF crop mode (step S17). When reading in the SPF crop mode (Yes in step S17), as the input processing unit 41, the control unit 11 moves the first carriage 55 to the reading position R2 corresponding to the gray color of the background color plate 51 to perform reading. Then, as described in the explanations of FIGS. 4 and 5, the scanner unit 15 reads an area slightly larger than the vertical and horizontal dimensions of the document (step S19). Then, the read image is temporarily stored in the storage device 13.

[0047] When reading without using the SPF crop mode (No in step S17), as the input processing unit 41, the control unit 11 moves the first carriage 55 to the reading position R1 corresponding to the white color of the background color plate 51 to perform reading. Then, as described in the explanations of FIGS. 6 and 7, the scanner unit 15 reads an area determined based on the document size detected by the document size detection unit before reading (step S21). Then, the read image is temporarily stored in the storage device 13.

[0048] Subsequently, as the job execution unit 11X, the control unit 11 determines whether the blank page skipping function is set (step S25). When the blank page skipping function is not set (No in step S25), as the document area determination unit 45, the control unit 11 determines the document area 26 based on the density difference or color difference between the ground color of the document and the gray color of the background color plate 51. As the output image generation unit 47, the control unit 11 performs crop processing based on the document area 26 and stores the output image in the storage device 13 (step S27). Then, when the output images for each page are complete, they are combined and output as a file (step S57 shown in FIG. 10).

[0049] On the other hand, when the blank page skipping function is set (Yes in step S25), as the job execution unit 11X, the control unit 11 determines whether the read image 24 was read in the SPF crop mode (step S31 shown in FIG. 9). If the read image is not the read image read in the SPF crop mode, as the blank paper determination unit 43, the control unit 11 determines the blank paper determination area 28 based on the entire area of the read image 24 as shown in FIGS. 6 and 7. After performing the blank paper determination (step S33), the process proceeds to step S49.

[0050] On the other hand, if it is the read image 24 read in the SPF crop mode (Yes in step S31), as the document area determination unit 45, the control unit 11 determines whether the document width detected by the document guide 35 is greater than the threshold value (step S35). When the document width is greater than the threshold value (Yes in step S35), the process differs between the mode of Embodiment 1 and the mode of Embodiment 2 described above. According to the mode of Embodiment 1, when the document width is greater than the threshold value, as the blank paper determination unit 43, the control unit 11 determines the blank paper determination unit based on the standard size detected by the document size detection unit including the conveyance path sensor 39, and performs the blank paper determination (in the mode of Embodiment 1, the determination process of S37 shown in FIG. 9 is skipped and the process proceeds to the process of step S45. Refer to FIGS. 6 and 7). Also, as the output image generation unit 47, the control unit 11 crops the read image 24 based on the standard size detected by the document size detection unit to obtain an output image, and temporarily stores it in the storage device 13 (step S47). Then, the process proceeds to step S49 described later.

[0051] According to the mode of Embodiment 2, when the document width is greater than the threshold value, as the blank paper determination unit 43, the control unit 11 determines whether the detected document width is within a predetermined range with respect to the predetermined length (executes the process of step S37). When the document width is within the predetermined range with respect to the predetermined length, that is, when it is any standard size or close to it (Yes in step S37), the control unit 11 proceeds to step S39 described later and determines the document area 26 and the blank paper determination area 28 by the SPF crop function. On the other hand, when the original document width is not within a predetermined range with respect to the predetermined length, that is, in the case of an irregular size (No in step s37), the control unit 11 proceeds with the process to the aforementioned step S45, and determines the blank paper determination area 28 based on the regular size detected by the original document size detection unit.

[0052] In the aforementioned step S35, when the original document width is less than or equal to the threshold value (No in step S35), the control unit 11 as the original document area determination unit 45 determines the original document area 26 based on the density difference or color difference between the ground color of the original document and the gray color of the background color plate 51 (step S39). Further, the control unit 11 as the blank paper determination unit 43 determines the blank paper determination area 28 based on the determined original document area, and performs a blank paper determination on the blank paper determination area 28 (step S41). Also, the control unit 11 as the output image generation unit 47 obtains an output image based on the original document area 26, excluding the page determined to be blank paper, and stores it in the memory (step S43). When the reading of each page is completed, the control unit 11 as the job execution unit 11X causes the UI display unit 19 to display the image or the number of pages of the page determined to be blank paper by the blank paper determination unit 43 (step S49). Then, it waits for an instruction for confirmation from the user (a loop via No in step S51 and No in step S53 shown in FIG. 10).

[0053] When an instruction to approve skipping of blank paper based on the result of the blank paper determination is received via the UI display unit 19 (Yes in step S51), the control unit 11 as the output image generation unit 47 deletes the blank paper page (step S55). Then, it outputs the images of each page stored in the storage device 13 as a file together (step S57), and ends the process of reading the original document. On the other hand, when an instruction for the user to cancel skipping of blank paper is received (Yes in step S55), the control unit 11 as the output image generation unit 47 outputs the images of each page as a file together without deleting the blank paper page (step S57). Then, it ends the process of reading the original document.

[0054] As described above, (i) The image reading apparatus according to the present invention includes a document feeding device that feeds one or more documents placed at a placement position to a reading position one by one, a document size detection unit that detects at least one of the vertical and horizontal lengths of the fed document before reading and associates a corresponding or approximate standard size among a plurality of standard sizes having a predetermined length in both vertical and horizontal directions, an image reading device that reads the document and its surroundings as an image at the reading position, a background color plate arranged to be read by the image reading device as the surrounding image, a document area determination unit that determines a document area by discriminating the outline of the document based on the density difference or color difference between the document and the background color plate in the read image, and a blank paper determination unit that determines a blank paper determination area for determining whether the read document is a blank paper. The blank paper determination unit determines the blank paper determination area based on the standard size associated by the document size detection unit when at least one of the vertical and horizontal lengths of the document detected by the document size detection unit is equal to or larger than a predetermined threshold size, and determines the blank paper determination area based on the document area when the size is below the threshold size.

[0055] In the present invention, the document size detection unit includes a sensor that detects the document size of each document before reading, and a processing unit that executes a process of associating a standard size with the document based on the detection. Specific embodiments of the sensor are, for example, those that detect the vertical and horizontal sizes of the document placed at the placement position to temporarily determine a standard size, and detect at least one of the vertical and horizontal sizes of the fed document in front of the reading position to determine the standard size associated with the document. An example of a more specific embodiment is a guide width detection mechanism that detects the position of a guide that can slide in the main scanning direction (perpendicular to the feeding direction) of the document fed from the placement position. It is assumed that the position of the guide is adjusted by the user according to the size of the document at the placement position. Further, it includes a sensor that detects the magnitude in the feeding direction (also referred to as the sub-scanning direction) of the document at the placement position. The document size detection unit may further include a main scanning detection sensor arranged in the document conveyance path from the placement position to the reading position as described above for Patent Document 1. The specific mode of the processing unit is a control circuit mainly composed of a processor and a memory.

[0056] Also, the standard sizes are several sizes of rectangular originals with the generally used vertical and horizontal lengths. Its specific modes are, for example, the sizes set in the image reading device such as A3, A4, A5, 11”×17”, 8.5”×11”, 5.5”×8.5”. However, it is not limited to those sizes, and it may be individually set or selected in the image reading device. The non-standard size refers to a size that is not a standard size. In this specification, the vertical and horizontal lengths of the standard size are called the default lengths. Furthermore, the image reading device scans the original to read an image. Its specific modes include, for example, linear image sensors such as CCD (Charge Coupled Device) and CIS (Contact Image Sensor), and their drive circuits and signal processing circuits.

[0057] The background color plate is a member arranged behind the conveyed original in the reading area where the image reading device reads the original. In the case of an original whose size in the main scanning direction is smaller than the size of the reading area, it is exposed in the area without the original in the main scanning direction. Also, it is exposed over the entire area in the main scanning direction before the leading edge of the original passes and after the trailing edge of the original passes. When discriminating the outline of the original, the background color plate at the reading position is other than the ground color (white) of the original (for example, gray). On the other hand, when not discriminating the outline of the original, that is, when performing a blank paper determination based on the standard size associated by the original size detection unit, the background color plate at the reading position may be the same color as the ground color (white) of the original.

[0058] Both the original area determination unit and the blank paper determination unit are realized by the organic combination of the processing of the image processing circuit and the processor. However, which of the image processing circuit and the processor mainly performs the processing depends on the content of the processing and the configuration of the image processing circuit. When performing blank page determination by determining a blank page determination area based on a fixed size associated by the manuscript size detection unit before reading, the blank page determination process is relatively simple and mainly has a high affinity with processes that can be executed by an image processing circuit. In this specification, when based on the associated fixed size, it is mainly assumed that the image processing circuit performs the blank page determination process. On the other hand, the blank page determination process when based on the manuscript area based on the outline of the manuscript is not as simple as when based on the aforementioned associated fixed size. If it is difficult to prepare an image processing circuit corresponding to the process, including from a cost aspect, it will mainly be processed by a processor.

[0059] Furthermore, a preferred embodiment of the present invention will be described. (ii) Instead of using the associated fixed size as the standard to be applied when the detected size of at least one of the vertical and horizontal lengths is larger than the threshold value, the blank page determination unit compares the detected length of at least one of the vertical and horizontal lengths with a predetermined length related to the fixed size associated with the manuscript, and if the difference between the detected length and the predetermined length is outside a predetermined range, the manuscript area is used as the standard, and only when within the predetermined range, the associated fixed size may be used as the standard. In this way, only when the length of at least one of the vertical and horizontal directions detected by the manuscript size detection unit is close to a fixed size manuscript of the predetermined length, the blank page determination is performed based on the fixed size associated by the manuscript size detection unit, and the processing time of the blank page determination can be saved. On the other hand, when the detected length of at least one of the vertical and horizontal directions is not close to a fixed size manuscript of the predetermined length, by performing the blank page determination based on the manuscript area determined by the SPF crop function, the blank page determination area can be accurately determined even for an irregular size.

[0060] (iii) The manuscript size detection unit may detect the length of at least one of the vertical and horizontal directions of the manuscript on the manuscript conveyance path from the placement position to the reading position. In this way, since the manuscript size detection unit detects the manuscript size on the manuscript conveyance path before the fed manuscript reaches the reading position, the manuscript size can be detected before reading.

[0061] (iv) The apparatus may further include a setting unit that receives a setting as to whether to fixedly use the original document area as the criterion applied to the determination of the blank paper determination area or to switch the criterion according to the relationship between at least one of the detected vertical and horizontal lengths and the threshold value. In this way, even for an original document with an indefinite size, it is possible to prioritize accurately determining the blank paper determination area and set it to perform blank paper determination based on the original document area fixedly determined by the SPF crop function. Alternatively, it is possible to set to switch the criterion for determining the blank paper determination area based on whether at least one of the vertical and horizontal lengths detected by the original document size detection unit is close to a fixed-size original document with a predetermined length. It can be set to either according to the usage situation of the image reading apparatus.

[0062] (v) When outputting the data of the original document read by the image reading device, the apparatus may further include a blank paper removal unit that suppresses the output of the original document determined to be a blank paper by the blank paper determination unit and outputs only the original documents determined not to be blank papers. In this way, when reading one or more original documents, it is possible to suppress the output of blank paper original documents based on the result determined by the blank paper determination unit.

[0063] (vi) One aspect of the present invention includes steps in which a computer feeds one or more original documents to a reading position one by one, detects at least one of the vertical and horizontal lengths of the fed original document before reading, and associates the corresponding or approximate fixed-size among a plurality of types of fixed sizes with a predetermined length in both vertical and horizontal directions, reads the original document as an image together with a background color plate that exposes the original document around it at the reading position, determines the original document area by discriminating the contour of the original document based on the density difference or color difference between the original document and the background color plate in the read image, and determines a blank paper determination area for determining whether the read original document is a blank paper. When at least one of the detected vertical and horizontal lengths of the original document is equal to or larger than a predetermined threshold value, the blank paper determination area is determined based on the fixed size associated with the original document, and when the size is below the threshold value, the blank paper determination area is determined based on the original document area. The method includes a control method for image reading.

[0064] Aspects of the present invention also include combinations of any of the above-described aspects. In addition to the above-described embodiments, there can be various modifications to the present invention. Such modifications should not be construed as not belonging to the scope of the present invention. The present invention should include the meaning equivalent to the claims and all modifications within the scope.

Description of Reference Numerals

[0065] 11: Control unit, 11C: Communication unit, 11F: File control unit, 11J: Job management unit, 11P: Image processing unit, 11U: Display control unit, 11X: Job execution unit, 13: Storage device, 14: Engine unit, 15: Scanner unit, 16: Document feeder, SPF, 17: Document table, 18: SPF reading window, 19: UI display unit, User interface display unit, 21, 22: Documents, 24: Read image, 26: Document area, 28: Blank paper determination area, 31: Document set tray, 33: Document discharge tray, 35: Document guide, 37: Document sensor, 39: Conveyor path sensor, 41: Input processing unit, 43: Blank paper determination unit, 45: Document area determination unit, 47: Output image generation unit 51: Background color plate, 55: First carriage, 57: Second carriage, 59: Optical lens, 61: Image sensor 100: Multifunction device R1, R2: Reading positions

Claims

1. A document feeder that feeds one or more documents in the placement position one by one to the reading position, a document size detection unit that detects at least one of the vertical and horizontal lengths of the fed document before reading and associates the corresponding or approximate standard size among a plurality of standard sizes with a predetermined length, an image reading device that reads the document and the area around the document as an image at the reading position, a background color plate arranged so as to be read by the image reading device as the image of the surrounding area, a document area determination unit that determines the document area by discriminating the outline of the document based on the density difference or color difference between the document and the background color plate in the read image, a blank paper determination unit that determines a blank paper determination area for determining whether the read document is a blank paper, and the blank paper determination unit determines the blank paper determination area based on the standard size associated by the document size detection unit when at least one of the vertical and horizontal lengths of the document detected by the document size detection unit is equal to or larger than a predetermined threshold value, and determines the blank paper determination area based on the document area when the size is below the threshold value. An image reading device.

2. Instead of using the associated standard size as the standard to be applied when the detected at least one of the vertical and horizontal lengths is larger than the threshold value, the blank paper determination unit compares the detected at least one of the vertical and horizontal lengths with the predetermined length according to the standard size associated with the document, and if the difference between the detected length and the predetermined length is outside a predetermined range, the document area is used as the standard, and only when within the predetermined range, the associated standard size is used as the standard. The image reading device according to claim 1.

3. The document size detection unit according to claim 1, which detects at least one of the vertical and horizontal lengths of the document on the document conveyance path from the placement position to the reading position.

4. The image reading device according to claim 1, further comprising a setting unit that accepts a setting of whether to fixedly use the document area as the standard for determining the blank paper determination area or to switch according to the relationship between the detected at least one of the vertical and horizontal lengths and the threshold value.

5. The image reading apparatus according to claim 1, further comprising a blank page removing unit that suppresses output of a document determined to be a blank page by the blank page determination unit and outputs only a document determined not to be a blank page when outputting data of a document read by the image reading device.

6. A computer performs a step of feeding a document consisting of one or more sheets one by one to a reading position, a step of detecting at least one of the vertical and horizontal lengths of the fed document before reading and associating a corresponding or approximate standard size among a plurality of standard sizes with vertical and horizontal dimensions equal to a predetermined length, a step of reading the document at the reading position as an image together with a background color plate that exposes the document around it, a step of determining a document area by discriminating the outline of the document based on the density difference or color difference between the document and the background color plate in the read image, a step of determining a blank page determination area for determining whether the read document is a blank page, and a method for controlling image reading, wherein when the detected length of at least one of the vertical and horizontal dimensions of the document is equal to or greater than a predetermined threshold size, the blank page determination area is determined based on the standard size associated with the document, and when the size is less than the threshold, the blank page determination area is determined based on the document area.

Images